-EOFError
-```
-
-Python raises an error called `EOFError` which basically means it found an *end of file* symbol (which is represented by `ctrl-d`) when it did not expect to see it.
-
-## Handling Exceptions
-
-We can handle exceptions using the `try..except` statement. We basically put our usual statements within the try-block and put all our error handlers in the except-block.
-
-Example (save as `exceptions_handle.py`):
-
-{% include "./programs/exceptions_handle.py" %}
-
-Output:
-
-{% include "./programs/exceptions_handle.txt" %}
-
-**How It Works**
-
-We put all the statements that might raise exceptions/errors inside the `try` block and then put handlers for the appropriate errors/exceptions in the `except` clause/block. The `except` clause can handle a single specified error or exception, or a parenthesized list of errors/exceptions. If no names of errors or exceptions are supplied, it will handle _all_ errors and exceptions.
-
-Note that there has to be at least one `except` clause associated with every `try` clause. Otherwise, what's the point of having a try block?
-
-If any error or exception is not handled, then the default Python handler is called which just stops the execution of the program and prints an error message. We have already seen this in action above.
-
-You can also have an `else` clause associated with a `try..except` block. The `else` clause is executed if no exception occurs.
-
-In the next example, we will also see how to get the exception object so that we can retrieve additional information.
-
-## Raising Exceptions
-
-You can _raise_ exceptions using the `raise` statement by providing the name of the error/exception and the exception object that is to be _thrown_.
-
-The error or exception that you can raise should be a class which directly or indirectly must be a derived class of the `Exception` class.
-
-Example (save as `exceptions_raise.py`):
-
-{% include "./programs/exceptions_raise.py" %}
-
-Output:
-
-{% include "./programs/exceptions_raise.txt" %}
-
-**How It Works**
-
-Here, we are creating our own exception type. This new exception type is called `ShortInputException`. It has two fields - `length` which is the length of the given input, and `atleast` which is the minimum length that the program was expecting.
-
-In the `except` clause, we mention the class of error which will be stored `as` the variable name to hold the corresponding error/exception object. This is analogous to parameters and arguments in a function call. Within this particular `except` clause, we use the `length` and `atleast` fields of the exception object to print an appropriate message to the user.
-
-## Try ... Finally {#try-finally}
-
-Suppose you are reading a file in your program. How do you ensure that the file object is closed properly whether or not an exception was raised? This can be done using the `finally` block.
-
-Save this program as `exceptions_finally.py`:
-
-{% include "./programs/exceptions_finally.py" %}
-
-Output:
-
-{% include "./programs/exceptions_finally.txt" %}
-
-**How It Works**
-
-We do the usual file-reading stuff, but we have arbitrarily introduced sleeping for 2 seconds after printing each line using the `time.sleep` function so that the program runs slowly (Python is very fast by nature). When the program is still running, press `ctrl + c` to interrupt/cancel the program.
-
-Observe that the `KeyboardInterrupt` exception is thrown and the program quits. However, before the program exits, the finally clause is executed and the file object is always closed.
-
-Note that we use `sys.stdout.flush()` after `print` so that it prints to the screen immediately.
-
-## The with statement {#with}
-
-Acquiring a resource in the `try` block and subsequently releasing the resource in the `finally` block is a common pattern. Hence, there is also a `with` statement that enables this to be done in a clean manner:
-
-Save as `exceptions_using_with.py`:
-
-{% include "./programs/exceptions_using_with.py" %}
-
-**How It Works**
-
-The output should be same as the previous example. The difference here is that we are using the `open` function with the `with` statement - we leave the closing of the file to be done automatically by `with open`.
-
-What happens behind the scenes is that there is a protocol used by the `with` statement. It fetches the object returned by the `open` statement, let's call it "thefile" in this case.
-
-It _always_ calls the `thefile.__enter__` function before starting the block of code under it and _always_ calls `thefile.__exit__` after finishing the block of code.
-
-So the code that we would have written in a `finally` block should be taken care of automatically by the `__exit__` method. This is what helps us to avoid having to use explicit `try..finally` statements repeatedly.
-
-More discussion on this topic is beyond scope of this book, so please refer [PEP 343](http://www.python.org/dev/peps/pep-0343/) for a comprehensive explanation.
-
-## Summary
-
-We have discussed the usage of the `try..except` and `try..finally` statements. We have seen how to create our own exception types and how to raise exceptions as well.
-
-Next, we will explore the Python Standard Library.
diff --git a/feedback.md b/feedback.md
deleted file mode 100644
index 78c6e059..00000000
--- a/feedback.md
+++ /dev/null
@@ -1,3 +0,0 @@
-# Feedback
-
-The book needs the help of its readers such as yourselves to point out any parts of the book which are not good, not comprehensible or are simply wrong. Please [write to the main author]({{ book.contactUrl }}) or the respective [translators](./translations.md#translations) with your comments and suggestions.
diff --git a/first_steps.md b/first_steps.md
deleted file mode 100644
index 72395d50..00000000
--- a/first_steps.md
+++ /dev/null
@@ -1,190 +0,0 @@
-# First Steps
-
-We will now see how to run a traditional 'Hello World' program in Python. This will teach you how to write, save and run Python programs.
-
-There are two ways of using Python to run your program - using the interactive interpreter prompt or using a source file. We will now see how to use both of these methods.
-
-## Using The Interpreter Prompt
-
-Open the terminal in your operating system (as discussed previously in the [Installation](./installation.md#installation) chapter) and then open the Python prompt by typing `python3` and pressing `[enter]` key.
-
-Once you have started Python, you should see `>>>` where you can start typing stuff. This is called the _Python interpreter prompt_.
-
-At the Python interpreter prompt, type:
-
-```python
-print("Hello World")
-```
-
-followed by the `[enter]` key. You should see the words `Hello World` printed to the screen.
-
-Here is an example of what you should be seeing, when using a Mac OS X computer. The details about the Python software will differ based on your computer, but the part from the prompt (i.e. from `>>>` onwards) should be the same regardless of the operating system.
-
-
-```python
-> python3
-Python 3.5.1 (default, Jan 14 2016, 06:54:11)
-[GCC 4.2.1 Compatible Apple LLVM 7.0.2 (clang-700.1.81)] on darwin
-Type "help", "copyright", "credits" or "license" for more information.
->>> print("Hello World")
-Hello World
-```
-
-Notice that Python gives you the output of the line immediately! What you just entered is a single Python _statement_. We use `print` to (unsurprisingly) print any value that you supply to it. Here, we are supplying the text `Hello World` and this is promptly printed to the screen.
-
-### How to Quit the Interpreter Prompt
-
-If you are using a GNU/Linux or OS X shell, you can exit the interpreter prompt by pressing `[ctrl + d]` or entering `exit()` (note: remember to include the parentheses, `()`) followed by the `[enter]` key.
-
-If you are using the Windows command prompt, press `[ctrl + z]` followed by the `[enter]` key.
-
-## Choosing An Editor
-
-We cannot type out our program at the interpreter prompt every time we want to run something, so we have to save them in files and can run our programs any number of times.
-
-To create our Python source files, we need an editor software where you can type and save. A good programmer's editor will make your life easier in writing the source files. Hence, the choice of an editor is crucial indeed. You have to choose an editor as you would choose a car you would buy. A good editor will help you write Python programs easily, making your journey more comfortable and helps you reach your destination (achieve your goal) in a much faster and safer way.
-
-One of the very basic requirements is _syntax highlighting_ where all the different parts of your Python program are colorized so that you can _see_ your program and visualize its running.
-
-If you have no idea where to start, I would recommend using [PyCharm Educational Edition](https://www.jetbrains.com/pycharm-edu/) software which is available on Windows, Mac OS X and GNU/Linux. Details in the next section.
-
-If you are using Windows, *do not use Notepad* - it is a bad choice because it does not do syntax highlighting and also importantly it does not support indentation of the text which is very important in our case as we will see later. Good editors will automatically do this.
-
-If you are an experienced programmer, then you must be already using [Vim](http://www.vim.org) or [Emacs](http://www.gnu.org/software/emacs/). Needless to say, these are two of the most powerful editors and you will benefit from using them to write your Python programs. I personally use both for most of my programs, and have even written an [entire book on Vim]({{ book.vimBookUrl }}).
-
-In case you are willing to take the time to learn Vim or Emacs, then I highly recommend that you do learn to use either of them as it will be very useful for you in the long run. However, as I mentioned before, beginners can start with PyCharm and focus the learning on Python rather than the editor at this moment.
-
-To reiterate, please choose a proper editor - it can make writing Python programs more fun and easy.
-
-## PyCharm {#pycharm}
-
-[PyCharm Educational Edition](https://www.jetbrains.com/pycharm-edu/) is a free editor which you can use for writing Python programs.
-
-When you open PyCharm, you'll see this, click on `Create New Project`:
-
-
-
-Select `Pure Python`:
-
-
-
-Change `untitled` to `helloworld` as the location of the project, you should see details similar to this:
-
-
-
-Click the `Create` button.
-
-Right-click on the `helloworld` in the sidebar and select `New` -> `Python File`:
-
-
-
-You will be asked to type the name, type `hello`:
-
-
-
-You can now see a file opened for you:
-
-
-
-Delete the lines that are already present, and now type the following:
-
-
-
-```python
-print("hello world")
-```
-Now right-click on what you typed (without selecting the text), and click on `Run 'hello'`.
-
-
-
-You should now see the output (what it prints) of your program:
-
-
-
-Phew! That was quite a few steps to get started, but henceforth, every time we ask you to create a new file, remember to just right-click on `helloworld` on the left -> `New` -> `Python File` and continue the same steps to type and run as shown above.
-
-You can find more information about PyCharm in the [PyCharm Quickstart](https://www.jetbrains.com/pycharm-educational/quickstart/) page.
-
-## Vim
-
-1. Install [Vim](http://www.vim.org)
- * Mac OS X users should install `macvim` package via [HomeBrew](http://brew.sh/)
- * Windows users should download the "self-installing executable" from [Vim website](http://www.vim.org/download.php)
- * GNU/Linux users should get Vim from their distribution's software repositories, e.g. Debian and Ubuntu users can install the `vim` package.
-2. Install [jedi-vim](https://github.com/davidhalter/jedi-vim) plugin for autocompletion.
-3. Install corresponding `jedi` python package : `pip install -U jedi`
-
-## Emacs
-
-1. Install [Emacs 24+](http://www.gnu.org/software/emacs/).
- * Mac OS X users should get Emacs from http://emacsformacosx.com
- * Windows users should get Emacs from http://ftp.gnu.org/gnu/emacs/windows/
- * GNU/Linux users should get Emacs from their distribution's software repositories, e.g. Debian and Ubuntu users can install the `emacs24` package.
-2. Install [ELPY](https://github.com/jorgenschaefer/elpy/wiki)
-
-## Using A Source File
-
-Now let's get back to programming. There is a tradition that whenever you learn a new programming language, the first program that you write and run is the 'Hello World' program - all it does is just say 'Hello World' when you run it. As Simon Cozens[^1] says, it is the "traditional incantation to the programming gods to help you learn the language better."
-
-Start your choice of editor, enter the following program and save it as `hello.py`.
-
-If you are using PyCharm, we have already [discussed how to run from a source file](#pycharm).
-
-For other editors, open a new file `hello.py` and type this:
-
-```python
-print("hello world")
-```
-
-Where should you save the file? To any folder for which you know the location of the folder. If you
-don't understand what that means, create a new folder and use that location to save and run all
-your Python programs:
-
-- `/tmp/py` on Mac OS X
-- `/tmp/py` on GNU/Linux
-- `C:\\py` on Windows
-
-To create the above folder (for the operating system you are using), use the `mkdir` command in the terminal, for example, `mkdir /tmp/py`.
-
-IMPORTANT: Always ensure that you give it the file extension of `.py`, for example, `foo.py`.
-
-To run your Python program:
-
-1. Open a terminal window (see the previous [Installation](./installation.md#installation) chapter on how to do that)
-2. **C**hange **d**irectory to where you saved the file, for example, `cd /tmp/py`
-3. Run the program by entering the command `python hello.py`. The output is as shown below.
-
-```
-$ python hello.py
-hello world
-```
-
-
-
-If you got the output as shown above, congratulations! - you have successfully run your first Python program. You have successfully crossed the hardest part of learning programming, which is, getting started with your first program!
-
-In case you got an error, please type the above program _exactly_ as shown above and run the program again. Note that Python is case-sensitive i.e. `print` is not the same as `Print` - note the lowercase `p` in the former and the uppercase `P` in the latter. Also, ensure there are no spaces or tabs before the first character in each line - we will see [why this is important](./basics.md#indentation) later.
-
-**How It Works**
-
-A Python program is composed of _statements_. In our first program, we have only one statement. In this statement, we call the `print` _statement_ to which we supply the text "hello world".
-
-## Getting Help
-
-If you need quick information about any function or statement in Python, then you can use the built-in `help` functionality. This is very useful especially when using the interpreter prompt. For example, run `help('len')` - this displays the help for the `len` function which is used to count number of items.
-
-TIP: Press `q` to exit the help.
-
-Similarly, you can obtain information about almost anything in Python. Use `help()` to learn more about using `help` itself!
-
-In case you need to get help for operators like `return`, then you need to put those inside quotes such as `help('return')` so that Python doesn't get confused on what we're trying to do.
-
-## Summary
-
-You should now be able to write, save and run Python programs at ease.
-
-Now that you are a Python user, let's learn some more Python concepts.
-
----
-
-[^1]: the author of the amazing 'Beginning Perl' book
diff --git a/floss.md b/floss.md
deleted file mode 100644
index 5ead80ea..00000000
--- a/floss.md
+++ /dev/null
@@ -1,41 +0,0 @@
-# Appendix: FLOSS {#floss}
-
-> NOTE: Please note that this section was written in 2003, so some of this will sound quaint to you :-)
-
-"Free/Libre and Open Source Software", in short, [FLOSS](http://en.wikipedia.org/wiki/FLOSS) is based on the concept of a community, which itself is based on the concept of sharing, and particularly the sharing of knowledge. FLOSS are free for usage, modification and redistribution.
-
-If you have already read this book, then you are already familiar with FLOSS since you have been using *Python* all along and Python is an open source software!
-
-Here are some examples of FLOSS to give an idea of the kind of things that community sharing and building can create:
-
-[Linux](http://www.kernel.org): This is a FLOSS OS kernel used in the GNU/Linux operating system. Linux, the kernel, was started by Linus Torvalds as a student. Android is based on Linux. Any website you use these days will mostly be running on Linux.
-
-[Ubuntu](http://www.ubuntu.com): This is a community-driven distribution, sponsored by Canonical and it is the most popular GNU/Linux distribution today. It allows you to install a plethora of FLOSS available and all this in an easy-to-use and easy-to-install manner. Best of all, you can just reboot your computer and run GNU/Linux off the CD! This allows you to completely try out the new OS before installing it on your computer. However, Ubuntu is not entirely free software; it contains proprietary drivers, firmware, and applications.
-
-[LibreOffice](http://www.libreoffice.org/): This is an excellent community-driven and developed office suite with a writer, presentation, spreadsheet and drawing components among other things. It can even open and edit MS Word and MS PowerPoint files with ease. It runs on almost all platforms and is entirely free, libre and open source software.
-
-[Mozilla Firefox](http://www.mozilla.org/products/firefox): This is _the_ best web browser. It is blazingly fast and has gained critical acclaim for its sensible and impressive features. The extensions concept allows any kind of plugins to be used.
-
-[Mono](http://www.mono-project.com): This is an open source implementation of the Microsoft .NET platform. It allows .NET applications to be created and run on GNU/Linux, Windows, FreeBSD, Mac OS and many other platforms as well.
-
-[Apache web server](http://httpd.apache.org): This is the popular open source web server. In fact, it is _the_ most popular web server on the planet! It runs nearly more than half of the websites out there. Yes, that's right - Apache handles more websites than all the competition (including Microsoft IIS) combined.
-
-[VLC Player](http://www.videolan.org/vlc/): This is a video player that can play anything from DivX to MP3 to Ogg to VCDs and DVDs to ... who says open source ain't fun? ;-)
-
-This list is just intended to give you a brief idea - there are many more excellent FLOSS out there, such as the Perl language, PHP language, Drupal content management system for websites, PostgreSQL database server, TORCS racing game, KDevelop IDE, Xine - the movie player, VIM editor, Quanta+ editor, Banshee audio player, GIMP image editing program, ... This list could go on forever.
-
-To get the latest buzz in the FLOSS world, check out the following websites:
-
-- [OMG! Ubuntu!](http://www.omgubuntu.co.uk/)
-- [Web Upd8](http://www.webupd8.org/)
-- [DistroWatch](http://www.distrowatch.com)
-- [Planet Debian](http://planet.debian.org/)
-
-Visit the following websites for more information on FLOSS:
-
-- [GitHub Explore](http://github.com/explore)
-- [Code Triage](http://www.codetriage.com/)
-- [SourceForge](http://www.sourceforge.net)
-- [FreshMeat](http://www.freshmeat.net)
-
-So, go ahead and explore the vast, free and open world of FLOSS!
diff --git a/functions.md b/functions.md
deleted file mode 100644
index 6b3e9440..00000000
--- a/functions.md
+++ /dev/null
@@ -1,217 +0,0 @@
-# Functions
-
-Functions are reusable pieces of programs. They allow you to give a name to a block of statements, allowing you to run that block using the specified name anywhere in your program and any number of times. This is known as *calling* the function. We have already used many built-in functions such as `len` and `range`.
-
-The function concept is probably *the* most important building block of any non-trivial software (in any programming language), so we will explore various aspects of functions in this chapter.
-
-Functions are defined using the `def` keyword. After this keyword comes an *identifier* name for the function, followed by a pair of parentheses which may enclose some names of variables, and by the final colon that ends the line. Next follows the block of statements that are part of this function. An example will show that this is actually very simple:
-
-Example (save as `function1.py`):
-
-{% include "./programs/function1.py" %}
-
-Output:
-
-{% include "./programs/function1.txt" %}
-
-**How It Works**
-
-We define a function called `say_hello` using the syntax as explained above. This function takes no parameters and hence there are no variables declared in the parentheses. Parameters to functions are just input to the function so that we can pass in different values to it and get back corresponding results.
-
-Notice that we can call the same function twice which means we do not have to write the same code again.
-
-## Function Parameters
-
-A function can take parameters, which are values you supply to the function so that the function
-can *do* something utilising those values. These parameters are just like variables except that the
-values of these variables are defined when we call the function and are already assigned values
-when the function runs.
-
-Parameters are specified within the pair of parentheses in the function definition, separated by
-commas. When we call the function, we supply the values in the same way. Note the terminology
-used - the names given in the function definition are called *parameters* whereas the values you
-supply in the function call are called *arguments*.
-
-Example (save as `function_param.py`):
-
-{% include "./programs/function_param.py" %}
-
-Output:
-
-{% include "./programs/function_param.txt" %}
-
-**How It Works**
-
-Here, we define a function called `print_max` that uses two parameters called `a` and `b`. We find out the greater number using a simple `if..else` statement and then print the bigger number.
-
-The first time we call the function `print_max`, we directly supply the numbers as arguments. In the second case, we call the function with variables as arguments. `print_max(x, y)` causes the value of argument `x` to be assigned to parameter `a` and the value of argument `y` to be assigned to parameter `b`. The `print_max` function works the same way in both cases.
-
-## Local Variables
-
-When you declare variables inside a function definition, they are not related in any way to other variables with the same names used outside the function - i.e. variable names are *local* to the function. This is called the *scope* of the variable. All variables have the scope of the block they are declared in starting from the point of definition of the name.
-
-Example (save as `function_local.py`):
-
-{% include "./programs/function_local.py" %}
-
-Output:
-
-{% include "./programs/function_local.txt" %}
-
-**How It Works**
-
-The first time that we print the *value* of the name *x* with the first line in the function's body, Python uses the value of the parameter declared in the main block, above the function definition.
-
-Next, we assign the value `2` to `x`. The name `x` is local to our function. So, when we change the value of `x` in the function, the `x` defined in the main block remains unaffected.
-
-With the last `print` statement, we display the value of `x` as defined in the main block, thereby confirming that it is actually unaffected by the local assignment within the previously called function.
-
-## The `global` statement {#global-statement}
-
-If you want to assign a value to a name defined at the top level of the program (i.e. not inside any kind of scope such as functions or classes), then you have to tell Python that the name is not local, but it is *global*. We do this using the `global` statement. It is impossible to assign a value to a variable defined outside a function without the `global` statement.
-
-You can use the values of such variables defined outside the function (assuming there is no variable with the same name within the function). However, this is not encouraged and should be avoided since it becomes unclear to the reader of the program as to where that variable's definition is. Using the `global` statement makes it amply clear that the variable is defined in an outermost block.
-
-Example (save as `function_global.py`):
-
-{% include "./programs/function_global.py" %}
-
-Output:
-
-{% include "./programs/function_global.txt" %}
-
-**How It Works**
-
-The `global` statement is used to declare that `x` is a global variable - hence, when we assign a value to `x` inside the function, that change is reflected when we use the value of `x` in the main block.
-
-You can specify more than one global variable using the same `global` statement e.g. `global x, y, z`.
-
-## Default Argument Values {#default-arguments}
-
-For some functions, you may want to make some parameters *optional* and use default values in case the user does not want to provide values for them. This is done with the help of default argument values. You can specify default argument values for parameters by appending to the parameter name in the function definition the assignment operator (`=`) followed by the default value.
-
-Note that the default argument value should be a constant. More precisely, the default argument value should be immutable - this is explained in detail in later chapters. For now, just remember this.
-
-Example (save as `function_default.py`):
-
-{% include "./programs/function_default.py" %}
-
-Output:
-
-{% include "./programs/function_default.txt" %}
-
-**How It Works**
-
-The function named `say` is used to print a string as many times as specified. If we don't supply a value, then by default, the string is printed just once. We achieve this by specifying a default argument value of `1` to the parameter `times`.
-
-In the first usage of `say`, we supply only the string and it prints the string once. In the second usage of `say`, we supply both the string and an argument `5` stating that we want to *say* the string message 5 times.
-
-> *CAUTION*
->
-> Only those parameters which are at the end of the parameter list can be given default argument
-> values i.e. you cannot have a parameter with a default argument value preceding a parameter without
-> a default argument value in the function's parameter list.
->
-> This is because the values are assigned to the parameters by position. For example,`def func(a,
-> b=5)` is valid, but `def func(a=5, b)` is *not valid*.
-
-## Keyword Arguments
-
-If you have some functions with many parameters and you want to specify only some of them, then you can give values for such parameters by naming them - this is called *keyword arguments* - we use the name (keyword) instead of the position (which we have been using all along) to specify the arguments to the function.
-
-There are two advantages - one, using the function is easier since we do not need to worry about the order of the arguments. Two, we can give values to only those parameters to which we want to, provided that the other parameters have default argument values.
-
-Example (save as `function_keyword.py`):
-
-{% include "./programs/function_keyword.py" %}
-
-Output:
-
-{% include "./programs/function_keyword.txt" %}
-
-**How It Works**
-
-The function named `func` has one parameter without a default argument value, followed by two parameters with default argument values.
-
-In the first usage, `func(3, 7)`, the parameter `a` gets the value `3`, the parameter `b` gets the value `7` and `c` gets the default value of `10`.
-
-In the second usage `func(25, c=24)`, the variable `a` gets the value of 25 due to the position of the argument. Then, the parameter `c` gets the value of `24` due to naming i.e. keyword arguments. The variable `b` gets the default value of `5`.
-
-In the third usage `func(c=50, a=100)`, we use keyword arguments for all specified values. Notice that we are specifying the value for parameter `c` before that for `a` even though `a` is defined before `c` in the function definition.
-
-## VarArgs parameters
-
-Sometimes you might want to define a function that can take _any_ number of parameters, i.e. **var**iable number of **arg**uments, this can be achieved by using the stars (save as `function_varargs.py`):
-
-{% include "./programs/function_varargs.py" %}
-
-Output:
-
-{% include "./programs/function_varargs.txt" %}
-
-**How It Works**
-
-When we declare a starred parameter such as `*param`, then all the positional arguments from that point till the end are collected as a tuple called 'param'.
-
-Similarly, when we declare a double-starred parameter such as `**param`, then all the keyword arguments from that point till the end are collected as a dictionary called 'param'.
-
-We will explore tuples and dictionaries in a [later chapter](./data_structures.md#data-structures).
-
-## The `return` statement {#return-statement}
-
-The `return` statement is used to *return* from a function i.e. break out of the function. We can optionally *return a value* from the function as well.
-
-Example (save as `function_return.py`):
-
-{% include "./programs/function_return.py" %}
-
-Output:
-
-{% include "./programs/function_return.txt" %}
-
-**How It Works**
-
-The `maximum` function returns the maximum of the parameters, in this case the numbers supplied to the function. It uses a simple `if..else` statement to find the greater value and then *returns* that value.
-
-Note that a `return` statement without a value is equivalent to `return None`. `None` is a special type in Python that represents nothingness. For example, it is used to indicate that a variable has no value if it has a value of `None`.
-
-Every function implicitly contains a `return None` statement at the end unless you have written your own `return` statement. You can see this by running `print(some_function())` where the function `some_function` does not use the `return` statement such as:
-
-```python
-def some_function():
- pass
-```
-
-The `pass` statement is used in Python to indicate an empty block of statements.
-
-> TIP: There is a built-in function called `max` that already implements the 'find maximum' functionality, so use this built-in function whenever possible.
-
-## DocStrings
-
-Python has a nifty feature called *documentation strings*, usually referred to by its shorter name *docstrings*. DocStrings are an important tool that you should make use of since it helps to document the program better and makes it easier to understand. Amazingly, we can even get the docstring back from, say a function, when the program is actually running!
-
-Example (save as `function_docstring.py`):
-
-{% include "./programs/function_docstring.py" %}
-
-Output:
-
-{% include "./programs/function_docstring.txt" %}
-
-**How It Works**
-
-A string on the first logical line of a function is the *docstring* for that function. Note that DocStrings also apply to [modules](./modules.md#modules) and [classes](./oop.md#oop) which we will learn about in the respective chapters.
-
-The convention followed for a docstring is a multi-line string where the first line starts with a capital letter and ends with a dot. Then the second line is blank followed by any detailed explanation starting from the third line. You are *strongly advised* to follow this convention for all your docstrings for all your non-trivial functions.
-
-We can access the docstring of the `print_max` function using the `__doc__` (notice the *double underscores*) attribute (name belonging to) of the function. Just remember that Python treats *everything* as an object and this includes functions. We'll learn more about objects in the chapter on [classes](./oop.md#oop).
-
-If you have used `help()` in Python, then you have already seen the usage of docstrings! What it does is just fetch the `__doc__` attribute of that function and displays it in a neat manner for you. You can try it out on the function above - just include `help(print_max)` in your program. Remember to press the `q` key to exit `help`.
-
-Automated tools can retrieve the documentation from your program in this manner. Therefore, I *strongly recommend* that you use docstrings for any non-trivial function that you write. The `pydoc` command that comes with your Python distribution works similarly to `help()` using docstrings.
-
-## Summary
-
-We have seen so many aspects of functions but note that we still haven't covered all aspects of them. However, we have already covered most of what you'll use regarding Python functions on an everyday basis.
-
-Next, we will see how to use as well as create Python modules.
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diff --git a/installation.md b/installation.md
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--- a/installation.md
+++ /dev/null
@@ -1,84 +0,0 @@
-# Installation {#installation}
-
-When we refer to "Python 3" in this book, we will be referring to any version of Python equal to or greater than version [Python {{ book.pythonVersion }}](https://www.python.org/downloads/).
-
-## Installation on Windows
-
-Visit https://www.python.org/downloads/ and download the latest version. At the time of this writing, it was Python 3.5.1
-The installation is just like any other Windows-based software.
-
-CAUTION: Make sure you check option `Add Python 3.5 to PATH`.
-
-To change install location, click on `Customize installation`, then `Next` and enter `C:\python35` as install location.
-
-If not checked, check `Add Python to environment variables`. This does the same thing as `Add Python 3.5 to PATH` on the first install screen.
-
-You can choose to install Launcher for all users or not, it does not matter much. Launcher is used to switch between different versions of Python installed.
-
-If your path was not set correctly, then follow these steps to fix it. Otherwise, go to `Running Python prompt on Windows`.
-
-NOTE: For people who already know programming, if you are familiar with Docker, check out [Python in Docker](https://hub.docker.com/_/python/) and [Docker on Windows](https://docs.docker.com/windows/).
-
-### DOS Prompt {#dos-prompt}
-
-If you want to be able to use Python from the Windows command line i.e. the DOS prompt, then you need to set the PATH variable appropriately.
-
-For Windows 2000, XP, 2003 , click on `Control Panel` -> `System` -> `Advanced` -> `Environment Variables`. Click on the variable named `PATH` in the _System Variables_ section, then select `Edit` and add `;C:\Python35` (please verify that this folder exists, it will be different for newer versions of Python) to the end of what is already there. Of course, use the appropriate directory name.
-
-
-For older versions of Windows, open the file `C:\AUTOEXEC.BAT` and add the line `PATH=%PATH%;C:\Python35` and restart the system. For Windows NT, use the `AUTOEXEC.NT` file.
-
-For Windows Vista:
-
-- Click Start and choose `Control Panel`
-- Click System, on the right you'll see "View basic information about your computer"
-- On the left is a list of tasks, the last of which is `Advanced system settings`. Click that.
-- The `Advanced` tab of the `System Properties` dialog box is shown. Click the `Environment Variables` button on the bottom right.
-- In the lower box titled `System Variables` scroll down to Path and click the `Edit` button.
-- Change your path as need be.
-- Restart your system. Vista didn't pick up the system path environment variable change until I restarted.
-
-For Windows 7 and 8:
-
-- Right click on Computer from your desktop and select `Properties` or click `Start` and choose `Control Panel` -> `System and Security` -> `System`. Click on `Advanced system settings` on the left and then click on the `Advanced` tab. At the bottom click on `Environment Variables` and under `System variables`, look for the `PATH` variable, select and then press `Edit`.
-- Go to the end of the line under Variable value and append `;C:\Python35` (please verify that this folder exists, it will be different for newer versions of Python) to the end of what is already there. Of course, use the appropriate folder name.
-- If the value was `%SystemRoot%\system32;` It will now become `%SystemRoot%\system32;C:\Python35`
-- Click `OK` and you are done. No restart is required, however you may have to close and reopen the command line.
-
-### Running Python prompt on Windows
-
-For Windows users, you can run the interpreter in the command line if you have [set the `PATH` variable appropriately](#dos-prompt).
-
-To open the terminal in Windows, click the start button and click `Run`. In the dialog box, type `cmd` and press `[enter]` key.
-
-Then, type `python` and ensure there are no errors.
-
-## Installation on Mac OS X
-
-For Mac OS X users, use [Homebrew](http://brew.sh): `brew install python3`.
-
-To verify, open the terminal by pressing `[Command + Space]` keys (to open Spotlight search), type `Terminal` and press `[enter]` key. Now, run `python3` and ensure there are no errors.
-
-## Installation on GNU/Linux
-
-For GNU/Linux users, use your distribution's package manager to install Python 3, e.g. on Debian & Ubuntu: `sudo apt-get update && sudo apt-get install python3`.
-
-To verify, open the terminal by opening the `Terminal` application or by pressing `Alt + F2` and entering `gnome-terminal`. If that doesn't work, please refer the documentation of your particular GNU/Linux distribution. Now, run `python3` and ensure there are no errors.
-
-You can see the version of Python on the screen by running:
-
-
-```
-$ python3 -V
-Python 3.5.1
-```
-
-NOTE: `$` is the prompt of the shell. It will be different for you depending on the settings of the operating system on your computer, hence I will indicate the prompt by just the `$` symbol.
-
-CAUTION: Output may be different on your computer, depending on the version of Python software installed on your computer.
-
-## Summary
-
-From now on, we will assume that you have Python installed on your system.
-
-Next, we will write our first Python program.
diff --git a/io.md b/io.md
deleted file mode 100644
index 17da7941..00000000
--- a/io.md
+++ /dev/null
@@ -1,118 +0,0 @@
-# Input and Output {#io}
-
-There will be situations where your program has to interact with the user. For example, you would want to take input from the user and then print some results back. We can achieve this using the `input()` function and `print` function respectively.
-
-For output, we can also use the various methods of the `str` (string) class. For example, you can use the `rjust` method to get a string which is right justified to a specified width. See `help(str)` for more details.
-
-Another common type of input/output is dealing with files. The ability to create, read and write files is essential to many programs and we will explore this aspect in this chapter.
-
-## Input from user
-
-Save this program as `io_input.py`:
-
-{% include "./programs/io_input.py" %}
-
-Output:
-
-{% include "./programs/io_input.txt" %}
-
-**How It Works**
-
-We use the slicing feature to reverse the text. We've already seen how we can make [slices from sequences](./data_structures.md#sequence) using the `seq[a:b]` code starting from position `a` to position `b`. We can also provide a third argument that determines the _step_ by which the slicing is done. The default step is `1` because of which it returns a continuous part of the text. Giving a negative step, i.e., `-1` will return the text in reverse.
-
-The `input()` function takes a string as argument and displays it to the user. Then it waits for the user to type something and press the return key. Once the user has entered and pressed the return key, the `input()` function will then return that text the user has entered.
-
-We take that text and reverse it. If the original text and reversed text are equal, then the text is a [palindrome](http://en.wiktionary.org/wiki/palindrome).
-
-### Homework exercise
-
-Checking whether a text is a palindrome should also ignore punctuation, spaces and case. For example, "Rise to vote, sir." is also a palindrome but our current program doesn't say it is. Can you improve the above program to recognize this palindrome?
-
-If you need a hint, the idea is that...[^1]
-
-## Files
-
-You can open and use files for reading or writing by creating an object of the `file` class and using its `read`, `readline` or `write` methods appropriately to read from or write to the file. The ability to read or write to the file depends on the mode you have specified for the file opening. Then finally, when you are finished with the file, you call the `close` method to tell Python that we are done using the file.
-
-Example (save as `io_using_file.py`):
-
-{% include "./programs/io_using_file.py" %}
-
-Output:
-
-{% include "./programs/io_using_file.txt" %}
-
-**How It Works**
-
-First, open a file by using the built-in `open` function and specifying the name of the file and the mode in which we want to open the file. The mode can be a read mode (`'r'`), write mode (`'w'`) or append mode (`'a'`). We can also specify whether we are reading, writing, or appending in text mode (`'t'`) or binary mode (`'b'`). There are actually many more modes available and `help(open)` will give you more details about them. By default, `open()` considers the file to be a 't'ext file and opens it in 'r'ead mode.
-
-In our example, we first open the file in write text mode and use the `write` method of the file object to write to the file and then we finally `close` the file.
-
-Next, we open the same file again for reading. We don't need to specify a mode because 'read text file' is the default mode. We read in each line of the file using the `readline` method in a loop. This method returns a complete line including the newline character at the end of the line. When an _empty_ string is returned, it means that we have reached the end of the file and we 'break' out of the loop.
-
-In the end, we finally `close` the file.
-
-Now, check the contents of the `poem.txt` file to confirm that the program has indeed written to and read from that file.
-
-## Pickle
-
-Python provides a standard module called `pickle` using which you can store _any_ plain Python object in a file and then get it back later. This is called storing the object *persistently*.
-
-Example (save as `io_pickle.py`):
-
-{% include "./programs/io_pickle.py" %}
-
-Output:
-
-{% include "./programs/io_pickle.txt" %}
-
-**How It Works**
-
-To store an object in a file, we have to first `open` the file in __w__rite __b__inary mode and then call the `dump` function of the `pickle` module. This process is called _pickling_.
-
-Next, we retrieve the object using the `load` function of the `pickle` module which returns the object. This process is called _unpickling_.
-
-## Unicode
-
-So far, when we have been writing and using strings, or reading and writing to a file, we have used simple English characters only.
-
-> NOTE: If you are using Python 2, and we want to be able to read and write other non-English languages, we need to use the `unicode` type, and it all starts with the character `u`, e.g. `u"hello world"`
-
-```python
->>> "hello world"
-'hello world'
->>> type("hello world")
-
->>> u"hello world"
-'hello world'
->>> type(u"hello world")
-
-```
-
-When we read or write to a file or when we talk to other computers on the Internet, we need to convert our unicode strings into a format that can be sent and received, and that format is called "UTF-8". We can read and write in that format, using a simple keyword argument to our standard `open` function:
-
-{% include "./programs/io_unicode.py" %}
-
-**How It Works**
-
-You can ignore the `import` statement for now, we'll explore that in detail in the [modules chapter](./modules.md#modules).
-
-Whenever we write a program that uses Unicode literals like we have used above, we have to make sure that Python itself is told that our program uses UTF-8, and we have to put `# encoding=utf-8` comment at the top of our program.
-
-We use `io.open` and provide the "encoding" and "decoding" argument to tell Python that we are using unicode.
-
-You should learn more about this topic by reading:
-
-- ["The Absolute Minimum Every Software Developer Absolutely, Positively Must Know About Unicode and Character Sets"](http://www.joelonsoftware.com/articles/Unicode.html)
-- [Python Unicode Howto](http://docs.python.org/3/howto/unicode.html)
-- [Pragmatic Unicode talk by Nat Batchelder](http://nedbatchelder.com/text/unipain.html)
-
-## Summary
-
-We have discussed various types of input/output, about file handling, about the pickle module and about Unicode.
-
-Next, we will explore the concept of exceptions.
-
----
-
-[^1]: Use a tuple (you can find a list of _all_ [punctuation marks here](http://grammar.ccc.commnet.edu/grammar/marks/marks.htm)) to hold all the forbidden characters, then use the membership test to determine whether a character should be removed or not, i.e. forbidden = (`!`, `?`, `.`, ...).
diff --git a/modules.md b/modules.md
deleted file mode 100644
index 01e4df5e..00000000
--- a/modules.md
+++ /dev/null
@@ -1,212 +0,0 @@
-# Modules
-
-You have seen how you can reuse code in your program by defining functions once. What if you wanted to reuse a number of functions in other programs that you write? As you might have guessed, the answer is modules.
-
-There are various methods of writing modules, but the simplest way is to create a file with a `.py` extension that contains functions and variables.
-
-Another method is to write the modules in the native language in which the Python interpreter itself was written. For example, you can write modules in the [C programming language](http://docs.python.org/3/extending/) and when compiled, they can be used from your Python code when using the standard Python interpreter.
-
-A module can be *imported* by another program to make use of its functionality. This is how we can use the Python standard library as well. First, we will see how to use the standard library modules.
-
-Example (save as `module_using_sys.py`):
-
-{% include "./programs/module_using_sys.py" %}
-
-Output:
-
-{% include "./programs/module_using_sys.txt" %}
-
-**How It Works**
-
-First, we *import* the `sys` module using the `import` statement. Basically, this translates to us telling Python that we want to use this module. The `sys` module contains functionality related to the Python interpreter and its environment i.e. the **sys**tem.
-
-When Python executes the `import sys` statement, it looks for the `sys` module. In this case, it is one of the built-in modules, and hence Python knows where to find it.
-
-If it was not a compiled module i.e. a module written in Python, then the Python interpreter will search for it in the directories listed in its `sys.path` variable. If the module is found, then the statements in the body of that module are run and the module is made *available* for you to use. Note that the initialization is done only the *first* time that we import a module.
-
-The `argv` variable in the `sys` module is accessed using the dotted notation i.e. `sys.argv`. It clearly indicates that this name is part of the `sys` module. Another advantage of this approach is that the name does not clash with any `argv` variable used in your program.
-
-The `sys.argv` variable is a *list* of strings (lists are explained in detail in a [later chapter](./data_structures.md#data-structures). Specifically, the `sys.argv` contains the list of *command line arguments* i.e. the arguments passed to your program using the command line.
-
-If you are using an IDE to write and run these programs, look for a way to specify command line arguments to the program in the menus.
-
-Here, when we execute `python module_using_sys.py we are arguments`, we run the module `module_using_sys.py` with the `python` command and the other things that follow are arguments passed to the program. Python stores the command line arguments in the `sys.argv` variable for us to use.
-
-Remember, the name of the script running is always the first element in the `sys.argv` list. So, in this case we will have `'module_using_sys.py'` as `sys.argv[0]`, `'we'` as `sys.argv[1]`, `'are'` as `sys.argv[2]` and `'arguments'` as `sys.argv[3]`. Notice that Python starts counting from 0 and not 1.
-
-The `sys.path` contains the list of directory names where modules are imported from. Observe that the first string in `sys.path` is empty - this empty string indicates that the current directory is also part of the `sys.path` which is same as the `PYTHONPATH` environment variable. This means that you can directly import modules located in the current directory. Otherwise, you will have to place your module in one of the directories listed in `sys.path`.
-
-Note that the current directory is the directory from which the program is launched. Run `import os; print(os.getcwd())` to find out the current directory of your program.
-
-## Byte-compiled .pyc files {#pyc}
-
-Importing a module is a relatively costly affair, so Python does some tricks to make it faster. One way is to create *byte-compiled* files with the extension `.pyc` which is an intermediate form that Python transforms the program into (remember the [introduction section](./about_python.md#interpreted) on how Python works?). This `.pyc` file is useful when you import the module the next time from a different program - it will be much faster since a portion of the processing required in importing a module is already done. Also, these byte-compiled files are platform-independent.
-
-NOTE: These `.pyc` files are usually created in the same directory as the corresponding `.py` files. If Python does not have permission to write to files in that directory, then the `.pyc` files will _not_ be created.
-
-## The from..import statement {#from-import-statement}
-
-If you want to directly import the `argv` variable into your program (to avoid typing the `sys.` everytime for it), then you can use the `from sys import argv` statement.
-
-> WARNING: In general, *avoid* using the `from..import` statement, use the `import` statement instead. This is because your program will avoid name clashes and will be more readable.
-
-Example:
-
-```python
-from math import sqrt
-print("Square root of 16 is", sqrt(16))
-```
-
-## A module's `__name__` {#module-name}
-
-Every module has a name and statements in a module can find out the name of their module. This is handy for the particular purpose of figuring out whether the module is being run standalone or being imported. As mentioned previously, when a module is imported for the first time, the code it contains gets executed. We can use this to make the module behave in different ways depending on whether it is being used by itself or being imported from another module. This can be achieved using the `__name__` attribute of the module.
-
-Example (save as `module_using_name.py`):
-
-{% include "./programs/module_using_name.py" %}
-
-Output:
-
-{% include "./programs/module_using_name.txt" %}
-
-**How It Works**
-
-Every Python module has its `__name__` defined. If this is `'__main__'`, that implies that the module is being run standalone by the user and we can take appropriate actions.
-
-## Making Your Own Modules
-
-Creating your own modules is easy, you've been doing it all along! This is because every Python program is also a module. You just have to make sure it has a `.py` extension. The following example should make it clear.
-
-Example (save as `mymodule.py`):
-
-{% include "./programs/mymodule.py" %}
-
-The above was a sample *module*. As you can see, there is nothing particularly special about it compared to our usual Python program. We will next see how to use this module in our other Python programs.
-
-Remember that the module should be placed either in the same directory as the program from which we import it, or in one of the directories listed in `sys.path`.
-
-Another module (save as `mymodule_demo.py`):
-
-{% include "./programs/mymodule_demo.py" %}
-
-Output:
-
-{% include "./programs/mymodule_demo.txt" %}
-
-**How It Works**
-
-Notice that we use the same dotted notation to access members of the module. Python makes good reuse of the same notation to give the distinctive 'Pythonic' feel to it so that we don't have to keep learning new ways to do things.
-
-Here is a version utilising the `from..import` syntax (save as `mymodule_demo2.py`):
-
-{% include "./programs/mymodule_demo2.py" %}
-
-The output of `mymodule_demo2.py` is same as the output of `mymodule_demo.py`.
-
-Notice that if there was already a `__version__` name declared in the module that imports mymodule, there would be a clash. This is also likely because it is common practice for each module to declare it's version number using this name. Hence, it is always recommended to prefer the `import` statement even though it might make your program a little longer.
-
-You could also use:
-
-```python
-from mymodule import *
-```
-
-This will import all public names such as `say_hi` but would not import `__version__` because it starts with double underscores.
-
-> WARNING: Remember that you should avoid using import-star, i.e. `from mymodule import *`.
-
-
-
-> **Zen of Python**
->
-> One of Python's guiding principles is that "Explicit is better than Implicit". Run `import this` in Python to learn more.
-
-## The `dir` function {#dir-function}
-
-Built-in `dir()` function returns list of names defined by an object.
-If the object is a module, this list includes functions, classes and variables, defined inside that module.
-
-This function can accept arguments.
-If the argument is the name of the module, function returns list of names from that specified module.
-If there is no argument, function returns list of names from the current module.
-
-Example:
-
-```python
-$ python
->>> import sys
-
-# get names of attributes in sys module
->>> dir(sys)
-['__displayhook__', '__doc__',
-'argv', 'builtin_module_names',
-'version', 'version_info']
-# only few entries shown here
-
-# get names of attributes for current module
->>> dir()
-['__builtins__', '__doc__',
-'__name__', '__package__']
-
-# create a new variable 'a'
->>> a = 5
-
->>> dir()
-['__builtins__', '__doc__', '__name__', '__package__', 'a']
-
-# delete/remove a name
->>> del a
-
->>> dir()
-['__builtins__', '__doc__', '__name__', '__package__']
-```
-
-**How It Works**
-
-First, we see the usage of `dir` on the imported `sys` module. We can see the huge list of attributes that it contains.
-
-Next, we use the `dir` function without passing parameters to it. By default, it returns the list of attributes for the current module. Notice that the list of imported modules is also part of this list.
-
-In order to observe the `dir` in action, we define a new variable `a` and assign it a value and then check `dir` and we observe that there is an additional value in the list of the same name. We remove the variable/attribute of the current module using the `del` statement and the change is reflected again in the output of the `dir` function.
-
-A note on `del` - this statement is used to *delete* a variable/name and after the statement has run, in this case `del a`, you can no longer access the variable `a` - it is as if it never existed before at all.
-
-Note that the `dir()` function works on *any* object. For example, run `dir(str)` for the attributes of the `str` (string) class.
-
-There is also a [`vars()`](http://docs.python.org/3/library/functions.html#vars) function which can potentially give you the attributes and their values, but it will not work for all cases.
-
-## Packages
-
-By now, you must have started observing the hierarchy of organizing your programs. Variables usually go inside functions. Functions and global variables usually go inside modules. What if you wanted to organize modules? That's where packages come into the picture.
-
-Packages are just folders of modules with a special `__init__.py` file that indicates to Python that this folder is special because it contains Python modules.
-
-Let's say you want to create a package called 'world' with subpackages 'asia', 'africa', etc. and these subpackages in turn contain modules like 'india', 'madagascar', etc.
-
-This is how you would structure the folders:
-
-```
-- /
- - world/
- - __init__.py
- - asia/
- - __init__.py
- - india/
- - __init__.py
- - foo.py
- - africa/
- - __init__.py
- - madagascar/
- - __init__.py
- - bar.py
-```
-
-Packages are just a convenience to hierarchically organize modules. You will see many instances of this in the [standard library](./stdlib.md#stdlib).
-
-## Summary
-
-Just like functions are reusable parts of programs, modules are reusable programs. Packages are another hierarchy to organize modules. The standard library that comes with Python is an example of such a set of packages and modules.
-
-We have seen how to use these modules and create our own modules.
-
-Next, we will learn about some interesting concepts called data structures.
diff --git a/more.md b/more.md
deleted file mode 100644
index 91552e09..00000000
--- a/more.md
+++ /dev/null
@@ -1,174 +0,0 @@
-# More
-
-So far we have covered a majority of the various aspects of Python that you will use. In this chapter, we will cover some more aspects that will make our knowledge of Python more well-rounded.
-
-## Passing tuples around
-
-Ever wished you could return two different values from a function? You can. All you have to do is use a tuple.
-
-```python
->>> def get_error_details():
-... return (2, 'details')
-...
->>> errnum, errstr = get_error_details()
->>> errnum
-2
->>> errstr
-'details'
-```
-
-Notice that the usage of `a, b = ` interprets the result of the expression as a tuple with two values.
-
-This also means the fastest way to swap two variables in Python is:
-
-```python
->>> a = 5; b = 8
->>> a, b
-(5, 8)
->>> a, b = b, a
->>> a, b
-(8, 5)
-```
-
-## Special Methods
-
-There are certain methods such as the `__init__` and `__del__` methods which have special significance in classes.
-
-Special methods are used to mimic certain behaviors of built-in types. For example, if you want to use the `x[key]` indexing operation for your class (just like you use it for lists and tuples), then all you have to do is implement the `__getitem__()` method and your job is done. If you think about it, this is what Python does for the `list` class itself!
-
-Some useful special methods are listed in the following table. If you want to know about all the special methods, [see the manual](http://docs.python.org/3/reference/datamodel.html#special-method-names).
-
-- `__init__(self, ...)`
- - This method is called just before the newly created object is returned for usage.
-
-- `__del__(self)`
- - Called just before the object is destroyed (which has unpredictable timing, so avoid using this)
-
-- `__str__(self)`
- - Called when we use the `print` function or when `str()` is used.
-
-- `__lt__(self, other)`
- - Called when the _less than_ operator (<) is used. Similarly, there are special methods for all the operators (+, >, etc.)
-
-- `__getitem__(self, key)`
- - Called when `x[key]` indexing operation is used.
-
-- `__len__(self)`
- - Called when the built-in `len()` function is used for the sequence object.
-
-## Single Statement Blocks
-
-We have seen that each block of statements is set apart from the rest by its own indentation level. Well, there is one caveat. If your block of statements contains only one single statement, then you can specify it on the same line of, say, a conditional statement or looping statement. The following example should make this clear:
-
-```python
->>> flag = True
->>> if flag: print('Yes')
-...
-Yes
-```
-
-Notice that the single statement is used in-place and not as a separate block. Although, you can use this for making your program _smaller_, I strongly recommend avoiding this short-cut method, except for error checking, mainly because it will be much easier to add an extra statement if you are using proper indentation.
-
-## Lambda Forms
-
-A `lambda` statement is used to create new function objects. Essentially, the `lambda` takes a parameter followed by a single expression only which becomes the body of the function and the value of this expression is returned by the new function.
-
-Example (save as `more_lambda.py`):
-
-{% include "./programs/more_lambda.py" %}
-
-Output:
-
-{% include "./programs/more_lambda.txt" %}
-
-**How It Works**
-
-Notice that the `sort` method of a `list` can take a `key` parameter which determines how the list is sorted (usually we know only about ascending or descending order). In our case, we want to do a custom sort, and for that we need to write a function but instead of writing a separate `def` block for a function that will get used in only this one place, we use a lambda expression to create a new function.
-
-## List Comprehension
-
-List comprehensions are used to derive a new list from an existing list. Suppose you have a list of numbers and you want to get a corresponding list with all the numbers multiplied by 2 only when the number itself is greater than 2. List comprehensions are ideal for such situations.
-
-Example (save as `more_list_comprehension.py`):
-
-{% include "./programs/more_list_comprehension.py" %}
-
-Output:
-
-{% include "./programs/more_list_comprehension.txt" %}
-
-**How It Works**
-
-Here, we derive a new list by specifying the manipulation to be done (`2*i`) when some condition is satisfied (`if i > 2`). Note that the original list remains unmodified.
-
-The advantage of using list comprehensions is that it reduces the amount of boilerplate code required when we use loops to process each element of a list and store it in a new list.
-
-## Receiving Tuples and Dictionaries in Functions
-
-There is a special way of receiving parameters to a function as a tuple or a dictionary using the `*` or `**` prefix respectively. This is useful when taking variable number of arguments in the function.
-
-```python
->>> def powersum(power, *args):
-... '''Return the sum of each argument raised to the specified power.'''
-... total = 0
-... for i in args:
-... total += pow(i, power)
-... return total
-...
->>> powersum(2, 3, 4)
-25
->>> powersum(2, 10)
-100
-```
-
-Because we have a `*` prefix on the `args` variable, all extra arguments passed to the function are stored in `args` as a tuple. If a `**` prefix had been used instead, the extra parameters would be considered to be key/value pairs of a dictionary.
-
-## The assert statement {#assert}
-
-The `assert` statement is used to assert that something is true. For example, if you are very sure that you will have at least one element in a list you are using and want to check this, and raise an error if it is not true, then `assert` statement is ideal in this situation. When the assert statement fails, an `AssertionError` is raised.
-
-```python
->>> mylist = ['item']
->>> assert len(mylist) >= 1
->>> mylist.pop()
-'item'
->>> assert len(mylist) >= 1
-Traceback (most recent call last):
- File "", line 1, in
-AssertionError
-```
-
-The `assert` statement should be used judiciously. Most of the time, it is better to catch exceptions, either handle the problem or display an error message to the user and then quit.
-
-## Decorators {#decorator}
-
-Decorators are a shortcut to applying wrapper functions. This is helpful to "wrap" functionality with the same code over and over again. For example, I created a `retry` decorator for myself that I can just apply to any function and if any exception is thrown during a run, it is retried again, till a maximum of 5 times and with a delay between each retry. This is especially useful for situations where you are trying to make a network call to a remote computer:
-
-{% include "./programs/more_decorator.py" %}
-
-Output:
-
-{% include "./programs/more_decorator.txt" %}
-
-**How It Works**
-
-See:
-
-- http://www.ibm.com/developerworks/linux/library/l-cpdecor.html
-- http://toumorokoshi.github.io/dry-principles-through-python-decorators.html
-
-## Differences between Python 2 and Python 3 {#two-vs-three}
-
-See:
-
-- ["Six" library](http://pythonhosted.org/six/)
-- [Porting to Python 3 Redux by Armin](http://lucumr.pocoo.org/2013/5/21/porting-to-python-3-redux/)
-- [Python 3 experience by PyDanny](http://pydanny.com/experiences-with-django-python3.html)
-- [Official Django Guide to Porting to Python 3](https://docs.djangoproject.com/en/dev/topics/python3/)
-- [Discussion on What are the advantages to python 3.x?](http://www.reddit.com/r/Python/comments/22ovb3/what_are_the_advantages_to_python_3x/)
-
-## Summary
-
-We have covered some more features of Python in this chapter and yet we haven't covered all the features of Python. However, at this stage, we have covered most of what you are ever going to use in practice. This is sufficient for you to get started with whatever programs you are going to create.
-
-Next, we will discuss how to explore Python further.
diff --git a/oop.md b/oop.md
deleted file mode 100644
index cb7096d9..00000000
--- a/oop.md
+++ /dev/null
@@ -1,184 +0,0 @@
-# Object Oriented Programming {#oop}
-
-In all the programs we wrote till now, we have designed our program around functions i.e. blocks of statements which manipulate data. This is called the _procedure-oriented_ way of programming. There is another way of organizing your program which is to combine data and functionality and wrap it inside something called an object. This is called the _object oriented_ programming paradigm. Most of the time you can use procedural programming, but when writing large programs or have a problem that is better suited to this method, you can use object oriented programming techniques.
-
-Classes and objects are the two main aspects of object oriented programming. A **class** creates a new _type_ where **objects** are **instances** of the class. An analogy is that you can have variables of type `int` which translates to saying that variables that store integers are variables which are instances (objects) of the `int` class.
-
-> **Note for Static Language Programmers**
->
-> Note that even integers are treated as objects (of the `int` class). This is unlike C++ and Java (before version 1.5) where integers are primitive native types.
->
-> See `help(int)` for more details on the class.
->
-> C# and Java 1.5 programmers will find this similar to the _boxing and unboxing_ concept.
-
-Objects can store data using ordinary variables that _belong_ to the object. Variables that belong to an object or class are referred to as **fields**. Objects can also have functionality by using functions that _belong_ to a class. Such functions are called **methods** of the class. This terminology is important because it helps us to differentiate between functions and variables which are independent and those which belong to a class or object. Collectively, the fields and methods can be referred to as the **attributes** of that class.
-
-Fields are of two types - they can belong to each instance/object of the class or they can belong to the class itself. They are called **instance variables** and **class variables** respectively.
-
-A class is created using the `class` keyword. The fields and methods of the class are listed in an indented block.
-
-## The `self` {#self}
-
-Class methods have only one specific difference from ordinary functions - they must have an extra first name that has to be added to the beginning of the parameter list, but you **do not** give a value for this parameter when you call the method, Python will provide it. This particular variable refers to the object _itself_, and by convention, it is given the name `self`.
-
-Although, you can give any name for this parameter, it is _strongly recommended_ that you use the name `self` - any other name is definitely frowned upon. There are many advantages to using a standard name - any reader of your program will immediately recognize it and even specialized IDEs (Integrated Development Environments) can help you if you use `self`.
-
-> **Note for C++/Java/C# Programmers**
->
-> The `self` in Python is equivalent to the `this` pointer in C++ and the `this` reference in Java and C#.
-
-You must be wondering how Python gives the value for `self` and why you don't need to give a value for it. An example will make this clear. Say you have a class called `MyClass` and an instance of this class called `myobject`. When you call a method of this object as `myobject.method(arg1, arg2)`, this is automatically converted by Python into `MyClass.method(myobject, arg1, arg2)` - this is all the special `self` is about.
-
-This also means that if you have a method which takes no arguments, then you still have to have one argument - the `self`.
-
-## Classes {#class}
-
-The simplest class possible is shown in the following example (save as `oop_simplestclass.py`).
-
-{% include "./programs/oop_simplestclass.py" %}
-
-Output:
-
-{% include "./programs/oop_simplestclass.txt" %}
-
-**How It Works**
-
-We create a new class using the `class` statement and the name of the class. This is followed by an indented block of statements which form the body of the class. In this case, we have an empty block which is indicated using the `pass` statement.
-
-Next, we create an object/instance of this class using the name of the class followed by a pair of parentheses. (We will learn <> in the next section). For our verification, we confirm the type of the variable by simply printing it. It tells us that we have an instance of the `Person` class in the `__main__` module.
-
-Notice that the address of the computer memory where your object is stored is also printed. The address will have a different value on your computer since Python can store the object wherever it finds space.
-
-## Methods
-
-We have already discussed that classes/objects can have methods just like functions except that we have an extra `self` variable. We will now see an example (save as `oop_method.py`).
-
-{% include "./programs/oop_method.py" %}
-
-Output:
-
-{% include "./programs/oop_method.txt" %}
-
-**How It Works**
-
-Here we see the `self` in action. Notice that the `say_hi` method takes no parameters but still has the `self` in the function definition.
-
-## The `__init__` method {#init}
-
-There are many method names which have special significance in Python classes. We will see the significance of the `__init__` method now.
-
-The `__init__` method is run as soon as an object of a class is instantiated. The method is useful to do any *initialization* you want to do with your object. Notice the double underscores both at the beginning and at the end of the name.
-
-Example (save as `oop_init.py`):
-
-{% include "./programs/oop_init.py" %}
-
-Output:
-
-{% include "./programs/oop_init.txt" %}
-
-**How It Works**
-
-Here, we define the `__init__` method as taking a parameter `name` (along with the usual `self`). Here, we just create a new field also called `name`. Notice these are two different variables even though they are both called 'name'. There is no problem because the dotted notation `self.name` means that there is something called "name" that is part of the object called "self" and the other `name` is a local variable. Since we explicitly indicate which name we are referring to, there is no confusion.
-
-When creating new instance `p`, of the class `Person`, we do so by using the class name, followed by the arguments in the parentheses: p = Person('Swaroop').
-
-We do not explicitly call the `__init__` method.
-This is the special significance of this method.
-
-Now, we are able to use the `self.name` field in our methods which is demonstrated in the `say_hi` method.
-
-## Class And Object Variables {#class-obj-vars}
-
-We have already discussed the functionality part of classes and objects (i.e. methods), now let us learn about the data part. The data part, i.e. fields, are nothing but ordinary variables that are _bound_ to the **namespaces** of the classes and objects. This means that these names are valid within the context of these classes and objects only. That's why they are called _name spaces_.
-
-There are two types of _fields_ - class variables and object variables which are classified depending on whether the class or the object _owns_ the variables respectively.
-
-**Class variables** are shared - they can be accessed by all instances of that class. There is only one copy of the class variable and when any one object makes a change to a class variable, that change will be seen by all the other instances.
-
-**Object variables** are owned by each individual object/instance of the class. In this case, each object has its own copy of the field i.e. they are not shared and are not related in any way to the field by the same name in a different instance. An example will make this easy to understand (save as `oop_objvar.py`):
-
-{% include "./programs/oop_objvar.py" %}
-
-Output:
-
-{% include "./programs/oop_objvar.txt" %}
-
-**How It Works**
-
-This is a long example but helps demonstrate the nature of class and object variables. Here, `population` belongs to the `Robot` class and hence is a class variable. The `name` variable belongs to the object (it is assigned using `self`) and hence is an object variable.
-
-Thus, we refer to the `population` class variable as `Robot.population` and not as `self.population`. We refer to the object variable `name` using `self.name` notation in the methods of that object. Remember this simple difference between class and object variables. Also note that an object variable with the same name as a class variable will hide the class variable!
-
-Instead of `Robot.population`, we could have also used `self.__class__.population` because every object refers to it's class via the `self.__class__` attribute.
-
-The `how_many` is actually a method that belongs to the class and not to the object. This means we can define it as either a `classmethod` or a `staticmethod` depending on whether we need to know which class we are part of. Since we refer to a class variable, let's use `classmethod`.
-
-We have marked the `how_many` method as a class method using a [decorator](./more.md#decorator).
-
-Decorators can be imagined to be a shortcut to calling a wrapper function, so applying the `@classmethod` decorator is same as calling:
-
-```python
-how_many = classmethod(how_many)
-```
-
-Observe that the `__init__` method is used to initialize the `Robot` instance with a name. In this method, we increase the `population` count by 1 since we have one more robot being added. Also observe that the values of `self.name` is specific to each object which indicates the nature of object variables.
-
-Remember, that you must refer to the variables and methods of the same object using the `self` *only*. This is called an *attribute reference*.
-
-In this program, we also see the use of *docstrings* for classes as well as methods. We can access the class docstring at runtime using `Robot.__doc__` and the method docstring as `Robot.say_hi.__doc__`
-
-In the `die` method, we simply decrease the `Robot.population` count by 1.
-
-All class members are public. One exception: If you use data members with names using the _double underscore prefix_ such as `__privatevar`, Python uses name-mangling to effectively make it a private variable.
-
-Thus, the convention followed is that any variable that is to be used only within the class or object should begin with an underscore and all other names are public and can be used by other classes/objects. Remember that this is only a convention and is not enforced by Python (except for the double underscore prefix).
-
-> **Note for C++/Java/C# Programmers**
->
-> All class members (including the data members) are _public_ and all the methods are _virtual_ in Python.
-
-## Inheritance
-
-One of the major benefits of object oriented programming is **reuse** of code and one of the ways this is achieved is through the **inheritance** mechanism. Inheritance can be best imagined as implementing a **type and subtype** relationship between classes.
-
-Suppose you want to write a program which has to keep track of the teachers and students in a college. They have some common characteristics such as name, age and address. They also have specific characteristics such as salary, courses and leaves for teachers and, marks and fees for students.
-
-You can create two independent classes for each type and process them but adding a new common characteristic would mean adding to both of these independent classes. This quickly becomes unwieldy.
-
-A better way would be to create a common class called `SchoolMember` and then have the teacher and student classes _inherit_ from this class i.e. they will become sub-types of this type (class) and then we can add specific characteristics to these sub-types.
-
-There are many advantages to this approach. If we add/change any functionality in `SchoolMember`, this is automatically reflected in the subtypes as well. For example, you can add a new ID card field for both teachers and students by simply adding it to the SchoolMember class. However, changes in the subtypes do not affect other subtypes. Another advantage is that if you can refer to a teacher or student object as a `SchoolMember` object which could be useful in some situations such as counting of the number of school members. This is called **polymorphism** where a sub-type can be substituted in any situation where a parent type is expected i.e. the object can be treated as an instance of the parent class.
-
-Also observe that we reuse the code of the parent class and we do not need to repeat it in the different classes as we would have had to in case we had used independent classes.
-
-The `SchoolMember` class in this situation is known as the **base class** or the **superclass**. The `Teacher` and `Student` classes are called the **derived classes** or **subclasses**.
-
-We will now see this example as a program (save as `oop_subclass.py`):
-
-{% include "./programs/oop_subclass.py" %}
-
-Output:
-
-{% include "./programs/oop_subclass.txt" %}
-
-**How It Works**
-
-To use inheritance, we specify the base class names in a tuple following the class name in the class definition. Next, we observe that the `__init__` method of the base class is explicitly called using the `self` variable so that we can initialize the base class part of the object. This is very important to remember - Python does not automatically call the constructor of the base class, you have to explicitly call it yourself.
-
-We also observe that we can call methods of the base class by prefixing the class name to the method call and then pass in the `self` variable along with any arguments.
-
-Notice that we can treat instances of `Teacher` or `Student` as just instances of the `SchoolMember` when we use the `tell` method of the `SchoolMember` class.
-
-Also, observe that the `tell` method of the subtype is called and not the `tell` method of the `SchoolMember` class. One way to understand this is that Python _always_ starts looking for methods in the actual type, which in this case it does. If it could not find the method, it starts looking at the methods belonging to its base classes one by one in the order they are specified in the tuple in the class definition.
-
-A note on terminology - if more than one class is listed in the inheritance tuple, then it is called **multiple inheritance**.
-
-The `end` parameter is used in the `print` function in the superclass's `tell()` method to print a line and allow the next print to continue on the same line. This is a trick to make `print` not print a `\n` (newline) symbol at the end of the printing.
-
-## Summary
-
-We have now explored the various aspects of classes and objects as well as the various terminologies associated with it. We have also seen the benefits and pitfalls of object-oriented programming. Python is highly object-oriented and understanding these concepts carefully will help you a lot in the long run.
-
-Next, we will learn how to deal with input/output and how to access files in Python.
diff --git a/op_exp.md b/op_exp.md
deleted file mode 100644
index 4cfcd7fb..00000000
--- a/op_exp.md
+++ /dev/null
@@ -1,204 +0,0 @@
-# Operators and Expressions {#op-exp}
-
-Most statements (logical lines) that you write will contain _expressions_. A simple example of an expression is `2 + 3`. An expression can be broken down into operators and operands.
-
-_Operators_ are functionality that do something and can be represented by symbols such as `+` or by special keywords. Operators require some data to operate on and such data is called _operands_. In this case, `2` and `3` are the operands.
-
-## Operators
-
-We will briefly take a look at the operators and their usage.
-
-Note that you can evaluate the expressions given in the examples using the interpreter interactively. For example, to test the expression `2 + 3`, use the interactive Python interpreter prompt:
-
-```python
->>> 2 + 3
-5
->>> 3 * 5
-15
->>>
-```
-
-Here is a quick overview of the available operators:
-
-- `+` (plus)
- - Adds two objects
- - `3 + 5` gives `8`. `'a' + 'b'` gives `'ab'`.
-
-- `-` (minus)
- - Gives the subtraction of one number from the other; if the first operand is absent it is assumed to be zero.
- - `-5.2` gives a negative number and `50 - 24` gives `26`.
-
-- `*` (multiply)
- - Gives the multiplication of the two numbers or returns the string repeated that many times.
- - `2 * 3` gives `6`. `'la' * 3` gives `'lalala'`.
-
-- `**` (power)
- - Returns x to the power of y
- - `3 ** 4` gives `81` (i.e. `3 * 3 * 3 * 3`)
-
-- `/` (divide)
- - Divide x by y
- - `13 / 3` gives `4.333333333333333`
-
-- `//` (divide and floor)
- - Divide x by y and round the answer _down_ to the nearest whole number
- - `13 // 3` gives `4`
- - `-13 // 3` gives `-5`
-
-- `%` (modulo)
- - Returns the remainder of the division
- - `13 % 3` gives `1`. `-25.5 % 2.25` gives `1.5`.
-
-- `<<` (left shift)
- - Shifts the bits of the number to the left by the number of bits specified. (Each number is represented in memory by bits or binary digits i.e. 0 and 1)
- - `2 << 2` gives `8`. `2` is represented by `10` in bits.
- - Left shifting by 2 bits gives `1000` which represents the decimal `8`.
-
-- `>>` (right shift)
- - Shifts the bits of the number to the right by the number of bits specified.
- - `11 >> 1` gives `5`.
- - `11` is represented in bits by `1011` which when right shifted by 1 bit gives `101`which is the decimal `5`.
-
-- `&` (bit-wise AND)
- - Bit-wise AND of the numbers
- - `5 & 3` gives `1`.
-
-- `|` (bit-wise OR)
- - Bitwise OR of the numbers
- - `5 | 3` gives `7`
-
-- `^` (bit-wise XOR)
- - Bitwise XOR of the numbers
- - `5 ^ 3` gives `6`
-
-- `~` (bit-wise invert)
- - The bit-wise inversion of x is -(x+1)
- - `~5` gives `-6`. More details at http://stackoverflow.com/a/11810203
-
-- `<` (less than)
- - Returns whether x is less than y. All comparison operators return `True` or `False`. Note the capitalization of these names.
- - `5 < 3` gives `False` and `3 < 5` gives `True`.
- - Comparisons can be chained arbitrarily: `3 < 5 < 7` gives `True`.
-
-- `>` (greater than)
- - Returns whether x is greater than y
- - `5 > 3` returns `True`. If both operands are numbers, they are first converted to a common type. Otherwise, it always returns `False`.
-
-- `<=` (less than or equal to)
- - Returns whether x is less than or equal to y
- - `x = 3; y = 6; x <= y` returns `True`
-
-- `>=` (greater than or equal to)
- - Returns whether x is greater than or equal to y
- - `x = 4; y = 3; x >= 3` returns `True`
-
-- `==` (equal to)
- - Compares if the objects are equal
- - `x = 2; y = 2; x == y` returns `True`
- - `x = 'str'; y = 'stR'; x == y` returns `False`
- - `x = 'str'; y = 'str'; x == y` returns `True`
-
-- `!=` (not equal to)
- - Compares if the objects are not equal
- - `x = 2; y = 3; x != y` returns `True`
-
-- `not` (boolean NOT)
- - If x is `True`, it returns `False`. If x is `False`, it returns `True`.
- - `x = True; not x` returns `False`.
-
-- `and` (boolean AND)
- - `x and y` returns `False` if x is `False`, else it returns evaluation of y
- - `x = False; y = True; x and y` returns `False` since x is False. In this case, Python will not evaluate y since it knows that the left hand side of the 'and' expression is `False` which implies that the whole expression will be `False` irrespective of the other values. This is called short-circuit evaluation.
-
-- `or` (boolean OR)
- - If x is `True`, it returns True, else it returns evaluation of y
- - `x = True; y = False; x or y` returns `True`. Short-circuit evaluation applies here as well.
-
-## Shortcut for math operation and assignment
-
-It is common to run a math operation on a variable and then assign the result of the operation back to the variable, hence there is a shortcut for such expressions:
-
-```python
-a = 2
-a = a * 3
-```
-
-can be written as:
-
-```python
-a = 2
-a *= 3
-```
-
-Notice that `var = var operation expression` becomes `var operation= expression`.
-
-## Evaluation Order
-
-If you had an expression such as `2 + 3 * 4`, is the addition done first or the multiplication? Our high school maths tells us that the multiplication should be done first. This means that the multiplication operator has higher precedence than the addition operator.
-
-The following table gives the precedence table for Python, from the lowest precedence (least binding) to the highest precedence (most binding). This means that in a given expression, Python will first evaluate the operators and expressions lower in the table before the ones listed higher in the table.
-
-The following table, taken from the [Python reference manual](http://docs.python.org/3/reference/expressions.html#operator-precedence), is provided for the sake of completeness. It is far better to use parentheses to group operators and operands appropriately in order to explicitly specify the precedence. This makes the program more readable. See [Changing the Order of Evaluation](#changing-order-of-evaluation) below for details.
-
-- `lambda` : Lambda Expression
-- `if - else` : Conditional expression
-- `or` : Boolean OR
-- `and` : Boolean AND
-- `not x` : Boolean NOT
-- `in, not in, is, is not, <, <=, >, >=, !=, ==` : Comparisons, including membership tests and identity tests
-- `|` : Bitwise OR
-- `^` : Bitwise XOR
-- `&` : Bitwise AND
-- `<<, >>` : Shifts
-- `+, -` : Addition and subtraction
-- `*, /, //, %` : Multiplication, Division, Floor Division and Remainder
-- `+x, -x, ~x` : Positive, Negative, bitwise NOT
-- `**` : Exponentiation
-- `x[index], x[index:index], x(arguments...), x.attribute` : Subscription, slicing, call, attribute reference
-- `(expressions...), [expressions...], {key: value...}, {expressions...}` : Binding or tuple display, list display, dictionary display, set display
-
-The operators which we have not already come across will be explained in later chapters.
-
-Operators with the _same precedence_ are listed in the same row in the above table. For example, `+` and `-` have the same precedence.
-
-## Changing the Order Of Evaluation {#changing-order-of-evaluation}
-
-To make the expressions more readable, we can use parentheses. For example, `2 + (3 * 4)` is definitely easier to understand than `2 + 3 * 4` which requires knowledge of the operator precedences. As with everything else, the parentheses should be used reasonably (do not overdo it) and should not be redundant, as in `(2 + (3 * 4))`.
-
-There is an additional advantage to using parentheses - it helps us to change the order of evaluation. For example, if you want addition to be evaluated before multiplication in an expression, then you can write something like `(2 + 3) * 4`.
-
-## Associativity
-
-Operators are usually associated from left to right. This means that operators with the same precedence are evaluated in a left to right manner. For example, `2 + 3 + 4` is evaluated as `(2 + 3) + 4`.
-
-## Expressions
-
-Example (save as `expression.py`):
-
-```python
-length = 5
-breadth = 2
-
-area = length * breadth
-print('Area is', area)
-print('Perimeter is', 2 * (length + breadth))
-```
-
-Output:
-
-```
-$ python expression.py
-Area is 10
-Perimeter is 14
-```
-
-**How It Works**
-
-The length and breadth of the rectangle are stored in variables by the same name. We use these to calculate the area and perimeter of the rectangle with the help of expressions. We store the result of the expression `length * breadth` in the variable +area+ and then print it using the +print+ function. In the second case, we directly use the value of the expression `2 * (length + breadth)`
-in the print function.
-
-Also, notice how Python _pretty-prints_ the output. Even though we have not specified a space between `'Area is'` and the variable `area`, Python puts it for us so that we get a clean nice output and the program is much more readable this way (since we don't need to worry about spacing in the strings we use for output). This is an example of how Python makes life easy for the programmer.
-
-## Summary
-
-We have seen how to use operators, operands and expressions - these are the basic building blocks of any program. Next, we will see how to make use of these in our programs using statements.
diff --git a/preface.md b/preface.md
deleted file mode 100644
index 67083560..00000000
--- a/preface.md
+++ /dev/null
@@ -1,23 +0,0 @@
-# Preface
-
-Python is probably one of the few programming languages which is both simple and powerful. This is good for beginners as well as for experts, and more importantly, is fun to program with. This book aims to help you learn this wonderful language and show how to get things done quickly and painlessly - in effect 'The Anti-venom to your programming problems'.
-
-## Who This Book Is For
-
-This book serves as a guide or tutorial to the Python programming language. It is mainly targeted at newbies. It is useful for experienced programmers as well.
-
-The aim is that if all you know about computers is how to save text files, then you can learn Python from this book. If you have previous programming experience, then you can also learn Python from this book.
-
-If you do have previous programming experience, you will be interested in the differences between Python and your favorite programming language - I have highlighted many such differences. A little warning though, Python is soon going to become your favorite programming language!
-
-## Official Website
-
-The official website of the book is {{ book.officialUrl }} where you can read the whole book online, download the latest versions of the book, [buy a printed hard copy]({{ book.buyBookUrl }}) and also send me feedback.
-
-## Something To Think About
-
-> There are two ways of constructing a software design: one way is to make it so simple that there are obviously no deficiencies; the other is to make it so complicated that there are no obvious deficiencies. -- C. A. R. Hoare
-
-
-
-> Success in life is a matter not so much of talent and opportunity as of concentration and perseverance. -- C. W. Wendte
diff --git a/problem_solving.md b/problem_solving.md
deleted file mode 100644
index f2a24aa8..00000000
--- a/problem_solving.md
+++ /dev/null
@@ -1,157 +0,0 @@
-# Problem Solving
-
-We have explored various parts of the Python language and now we will take a look at how all these parts fit together, by designing and writing a program which _does_ something useful. The idea is to learn how to write a Python script on your own.
-
-## The Problem
-
-The problem we want to solve is:
-
-> I want a program which creates a backup of all my important files.
-
-Although, this is a simple problem, there is not enough information for us to get started with the solution. A little more *analysis* is required. For example, how do we specify _which_ files are to be backed up? _How_ are they stored? _Where_ are they stored?
-
-After analyzing the problem properly, we *design* our program. We make a list of things about how our program should work. In this case, I have created the following list on how _I_ want it to work. If you do the design, you may not come up with the same kind of analysis since every person has their own way of doing things, so that is perfectly okay.
-
-- The files and directories to be backed up are specified in a list.
-- The backup must be stored in a main backup directory.
-- The files are backed up into a zip file.
-- The name of the zip archive is the current date and time.
-- We use the standard `zip` command available by default in any standard GNU/Linux or Unix distribution. Note that you can use any archiving command you want as long as it has a command line interface.
-
-> **For Windows users**
->
-> Windows users can [install](http://gnuwin32.sourceforge.net/downlinks/zip.php) the `zip` command from the [GnuWin32 project page](http://gnuwin32.sourceforge.net/packages/zip.htm) and add `C:\Program Files\GnuWin32\bin` to your system `PATH` environment variable, similar to [what we did for recognizing the python command itself](./installation.md#dos-prompt).
-
-## The Solution
-
-As the design of our program is now reasonably stable, we can write the code which is an *implementation* of our solution.
-
-Save as `backup_ver1.py`:
-
-{% include "./programs/backup_ver1.py" %}
-
-Output:
-
-{% include "./programs/backup_ver1.txt" %}
-
-Now, we are in the *testing* phase where we test that our program works properly. If it doesn't behave as expected, then we have to *debug* our program i.e. remove the *bugs* (errors) from the program.
-
-If the above program does not work for you, copy the line printed after the `Zip command is` line in the output, paste it in the shell (on GNU/Linux and Mac OS X) / `cmd` (on Windows), see what the error is and try to fix it. Also check the zip command manual on what could be wrong. If this command succeeds, then the problem might be in the Python program itself, so check if it exactly matches the program written above.
-
-**How It Works**
-
-You will notice how we have converted our *design* into *code* in a step-by-step manner.
-
-We make use of the `os` and `time` modules by first importing them. Then, we specify the files and directories to be backed up in the `source` list. The target directory is where we store all the backup files and this is specified in the `target_dir` variable. The name of the zip archive that we are going to create is the current date and time which we generate using the `time.strftime()` function. It will also have the `.zip` extension and will be stored in the `target_dir` directory.
-
-Notice the use of the `os.sep` variable - this gives the directory separator according to your operating system i.e. it will be `'/'` in GNU/Linux and Unix, it will be `'\\'` in Windows and `':'` in Mac OS. Using `os.sep` instead of these characters directly will make our program portable and work across all of these systems.
-
-The `time.strftime()` function takes a specification such as the one we have used in the above program. The `%Y` specification will be replaced by the year with the century. The `%m` specification will be replaced by the month as a decimal number between `01` and `12` and so on. The complete list of such specifications can be found in the [Python Reference Manual](http://docs.python.org/3/library/time.html#time.strftime).
-
-We create the name of the target zip file using the addition operator which _concatenates_ the strings i.e. it joins the two strings together and returns a new one. Then, we create a string `zip_command` which contains the command that we are going to execute. You can check if this command works by running it in the shell (GNU/Linux terminal or DOS prompt).
-
-The `zip` command that we are using has some options and parameters passed. The `-r` option specifies that the zip command should work **r**ecursively for directories i.e. it should include all the subdirectories and files. The two options are combined and specified in a shortcut as `-qr`. The options are followed by the name of the zip archive to create followed by the list of files and directories to backup. We convert the `source` list into a string using the `join` method of strings which we have already seen how to use.
-
-Then, we finally *run* the command using the `os.system` function which runs the command as if it was run from the *system* i.e. in the shell - it returns `0` if the command was successfully, else it returns an error number.
-
-Depending on the outcome of the command, we print the appropriate message that the backup has failed or succeeded.
-
-That's it, we have created a script to take a backup of our important files!
-
-> **Note to Windows Users**
->
-> Instead of double backslash escape sequences, you can also use raw strings. For example, use `'C:\\Documents'` or `r'C:\Documents'`. However, do *not* use `'C:\Documents'` since you end up using an unknown escape sequence `\D`.
-
-Now that we have a working backup script, we can use it whenever we want to take a backup of the files. This is called the *operation* phase or the *deployment* phase of the software.
-
-The above program works properly, but (usually) first programs do not work exactly as you expect. For example, there might be problems if you have not designed the program properly or if you have made a mistake when typing the code, etc. Appropriately, you will have to go back to the design phase or you will have to debug your program.
-
-## Second Version
-
-The first version of our script works. However, we can make some refinements to it so that it can work better on a daily basis. This is called the *maintenance* phase of the software.
-
-One of the refinements I felt was useful is a better file-naming mechanism - using the _time_ as the name of the file within a directory with the current _date_ as a directory within the main backup directory. The first advantage is that your backups are stored in a hierarchical manner and therefore it is much easier to manage. The second advantage is that the filenames are much shorter. The third advantage is that separate directories will help you check if you have made a backup for each day since the directory would be created only if you have made a backup for that day.
-
-Save as `backup_ver2.py`:
-
-{% include "./programs/backup_ver2.py" %}
-
-Output:
-
-{% include "./programs/backup_ver2.txt" %}
-
-**How It Works**
-
-Most of the program remains the same. The changes are that we check if there is a directory with the current day as its name inside the main backup directory using the `os.path.exists` function. If it doesn't exist, we create it using the `os.mkdir` function.
-
-## Third Version
-
-The second version works fine when I do many backups, but when there are lots of backups, I am finding it hard to differentiate what the backups were for! For example, I might have made some major changes to a program or presentation, then I want to associate what those changes are with the name of the zip archive. This can be easily achieved by attaching a user-supplied comment to the name of the zip archive.
-
-WARNING: The following program does not work, so do not be alarmed, please follow along because there's a lesson in here.
-
-Save as `backup_ver3.py`:
-
-{% include "./programs/backup_ver3.py" %}
-
-Output:
-
-{% include "./programs/backup_ver3.txt" %}
-
-**How This (does not) Work**
-
-*This program does not work!* Python says there is a syntax error which means that the script does not satisfy the structure that Python expects to see. When we observe the error given by Python, it also tells us the place where it detected the error as well. So we start *debugging* our program from that line.
-
-On careful observation, we see that the single logical line has been split into two physical lines but we have not specified that these two physical lines belong together. Basically, Python has found the addition operator (`+`) without any operand in that logical line and hence it doesn't know how to continue. Remember that we can specify that the logical line continues in the next physical line by the use of a backslash at the end of the physical line. So, we make this correction to our program. This correction of the program when we find errors is called *bug fixing*.
-
-## Fourth Version
-
-Save as `backup_ver4.py`:
-
-{% include "./programs/backup_ver4.py" %}
-
-Output:
-
-{% include "./programs/backup_ver4.txt" %}
-
-**How It Works**
-
-This program now works! Let us go through the actual enhancements that we had made in version 3. We take in the user's comments using the `input` function and then check if the user actually entered something by finding out the length of the input using the `len` function. If the user has just pressed `enter` without entering anything (maybe it was just a routine backup or no special changes were made), then we proceed as we have done before.
-
-However, if a comment was supplied, then this is attached to the name of the zip archive just before the `.zip` extension. Notice that we are replacing spaces in the comment with underscores - this is because managing filenames without spaces is much easier.
-
-## More Refinements
-
-The fourth version is a satisfactorily working script for most users, but there is always room for improvement. For example, you can include a _verbosity_ level for the program where you can specify a `-v` option to make your program become more talkative or a `-q` to make it _quiet_.
-
-Another possible enhancement would be to allow extra files and directories to be passed to the script at the command line. We can get these names from the `sys.argv` list and we can add them to our `source` list using the `extend` method provided by the `list` class.
-
-The most important refinement would be to not use the `os.system` way of creating archives and instead using the [zipfile](http://docs.python.org/3/library/zipfile.html) or [tarfile](http://docs.python.org/3/library/tarfile.html) built-in modules to create these archives. They are part of the standard library and available already for you to use without external dependencies on the zip program to be available on your computer.
-
-However, I have been using the `os.system` way of creating a backup in the above examples purely for pedagogical purposes, so that the example is simple enough to be understood by everybody but real enough to be useful.
-
-Can you try writing the fifth version that uses the [zipfile](http://docs.python.org/3/library/zipfile.html) module instead of the `os.system` call?
-
-## The Software Development Process
-
-We have now gone through the various *phases* in the process of writing a software. These phases can be summarised as follows:
-
-1. What (Analysis)
-2. How (Design)
-3. Do It (Implementation)
-4. Test (Testing and Debugging)
-5. Use (Operation or Deployment)
-6. Maintain (Refinement)
-
-A recommended way of writing programs is the procedure we have followed in creating the backup script: Do the analysis and design. Start implementing with a simple version. Test and debug it. Use it to ensure that it works as expected. Now, add any features that you want and continue to repeat the Do It-Test-Use cycle as many times as required.
-
-Remember:
-
-> Software is grown, not built.
-> -- [Bill de hÓra](http://97things.oreilly.com/wiki/index.php/Great_software_is_not_built,_it_is_grown)
-
-## Summary
-
-We have seen how to create our own Python programs/scripts and the various stages involved in writing such programs. You may find it useful to create your own program just like we did in this chapter so that you become comfortable with Python as well as problem-solving.
-
-Next, we will discuss object-oriented programming.
diff --git a/programs/backup_ver1.py b/programs/backup_ver1.py
index 3841630c..5d1b1168 100644
--- a/programs/backup_ver1.py
+++ b/programs/backup_ver1.py
@@ -1,37 +1,37 @@
import os
import time
-# 1. The files and directories to be backed up are
-# specified in a list.
-# Example on Windows:
+# 1. 需要备份的文件与目录将被
+# 指定在一个列表中。
+# 例如在 Windows 下：
# source = ['"C:\\My Documents"', 'C:\\Code']
-# Example on Mac OS X and Linux:
+# 又例如在 Mac OS X 与 Linux 下：
source = ['/Users/swa/notes']
-# Notice we had to use double quotes inside the string
-# for names with spaces in it.
+# 在这里要注意到我们必须在字符串中使用双引号
+# 用以括起其中包含空格的名称。
-# 2. The backup must be stored in a
-# main backup directory
-# Example on Windows:
+#2. 备份文件必须存储在一个
+#主备份目录中
+#例如在 Windows 下：
# target_dir = 'E:\\Backup'
-# Example on Mac OS X and Linux:
+# 又例如在 Mac OS X 和 Linux 下：
target_dir = '/Users/swa/backup'
-# Remember to change this to which folder you will be using
+# 要记得将这里的目录地址修改至你将使用的路径
-# 3. The files are backed up into a zip file.
-# 4. The name of the zip archive is the current date and time
+# 3. 备份文件将打包压缩成 zip 文件。
+# 4. zip 压缩文件的文件名由当前日期与时间构成。
target = target_dir + os.sep + \
time.strftime('%Y%m%d%H%M%S') + '.zip'
-# Create target directory if it is not present
+# 如果目标目录还不存在，则进行创建
if not os.path.exists(target_dir):
- os.mkdir(target_dir) # make directory
+ os.mkdir(target_dir) # 创建目录
-# 5. We use the zip command to put the files in a zip archive
+# 5. 我们使用 zip 命令将文件打包成 zip 格式
zip_command = 'zip -r {0} {1}'.format(target,
' '.join(source))
-# Run the backup
+# 运行备份
print('Zip command is:')
print(zip_command)
print('Running:')
diff --git a/programs/backup_ver2.py b/programs/backup_ver2.py
index caebb985..8b4bd094 100644
--- a/programs/backup_ver2.py
+++ b/programs/backup_ver2.py
@@ -1,47 +1,46 @@
import os
import time
-# 1. The files and directories to be backed up are
-# specified in a list.
-# Example on Windows:
+# 1. 需要备份的文件与目录将被
+# 指定在一个列表中。
+# 例如在 Windows 下：
# source = ['"C:\\My Documents"', 'C:\\Code']
-# Example on Mac OS X and Linux:
+# 又例如在 Mac OS X 与 Linux 下：
source = ['/Users/swa/notes']
-# Notice we had to use double quotes inside the string
-# for names with spaces in it.
+# 在这里要注意到我们必须在字符串中使用双引号
+# 用以括起其中包含空格的名称。
-# 2. The backup must be stored in a
-# main backup directory
-# Example on Windows:
+# 2. 备份文件必须存储在一个
+# 主备份目录中
+# 例如在 Windows 下：
# target_dir = 'E:\\Backup'
-# Example on Mac OS X and Linux:
+# 又例如在 Mac OS X 和 Linux 下：
target_dir = '/Users/swa/backup'
-# Remember to change this to which folder you will be using
+# 要记得将这里的目录地址修改至你将使用的路径
-# Create target directory if it is not present
+# 如果目标目录不存在则创建目录
if not os.path.exists(target_dir):
- os.mkdir(target_dir) # make directory
+ os.mkdir(target_dir) # 创建目录
-# 3. The files are backed up into a zip file.
-# 4. The current day is the name of the subdirectory
-# in the main directory.
+# 3. 备份文件将打包压缩成 zip 文件。
+# 4. 将当前日期作为主备份目录下的子目录名称
today = target_dir + os.sep + time.strftime('%Y%m%d')
-# The current time is the name of the zip archive.
+# 将当前时间作为 zip 文件的文件名
now = time.strftime('%H%M%S')
-# The name of the zip file
+# zip 文件名称格式
target = today + os.sep + now + '.zip'
-# Create the subdirectory if it isn't already there
+# 如果子目录尚不存在则创建一个
if not os.path.exists(today):
os.mkdir(today)
print('Successfully created directory', today)
-# 5. We use the zip command to put the files in a zip archive
+# 5. 我们使用 zip 命令将文件打包成 zip 格式
zip_command = 'zip -r {0} {1}'.format(target,
' '.join(source))
-# Run the backup
+# 运行备份
print('Zip command is:')
print(zip_command)
print('Running:')
diff --git a/programs/backup_ver3.py b/programs/backup_ver3.py
index ac83aca8..81d7b6da 100644
--- a/programs/backup_ver3.py
+++ b/programs/backup_ver3.py
@@ -1,54 +1,54 @@
import os
import time
-# 1. The files and directories to be backed up are
-# specified in a list.
-# Example on Windows:
+# 1. 需要备份的文件与目录将被
+# 指定在一个列表中。
+# 例如在 Windows 下：
# source = ['"C:\\My Documents"', 'C:\\Code']
-# Example on Mac OS X and Linux:
+# 又例如在 Mac OS X 与 Linux 下：
source = ['/Users/swa/notes']
-# Notice we had to use double quotes inside the string
-# for names with spaces in it.
+# 在这里要注意到我们必须在字符串中使用双引号
+# 用以括起其中包含空格的名称。
-# 2. The backup must be stored in a
-# main backup directory
-# Example on Windows:
+# 2. 备份文件必须存储在一个
+# 主备份目录中
+# 例如在 Windows 下：
# target_dir = 'E:\\Backup'
-# Example on Mac OS X and Linux:
+# 又例如在 Mac OS X 和 Linux 下：
target_dir = '/Users/swa/backup'
-# Remember to change this to which folder you will be using
+# 要记得将这里的目录地址修改至你将使用的路径
-# Create target directory if it is not present
+# 如果目标目录还不存在，则进行创建
if not os.path.exists(target_dir):
- os.mkdir(target_dir) # make directory
+ os.mkdir(target_dir) # 创建目录
-# 3. The files are backed up into a zip file.
-# 4. The current day is the name of the subdirectory
-# in the main directory.
+# 3. 备份文件将打包压缩成 zip 文件。
+# 4. 将当前日期作为主备份目录下的
+# 子目录名称
today = target_dir + os.sep + time.strftime('%Y%m%d')
-# The current time is the name of the zip archive.
+# 将当前时间作为 zip 文件的文件名
now = time.strftime('%H%M%S')
-# Take a comment from the user to
-# create the name of the zip file
+# 添加一条来自用户的注释以创建
+# zip 文件的文件名
comment = input('Enter a comment --> ')
-# Check if a comment was entered
+# 检查是否有评论键入
if len(comment) == 0:
target = today + os.sep + now + '.zip'
else:
- target = today + os.sep + now + '_' +
+ target = today + os.sep + now + '_' +
comment.replace(' ', '_') + '.zip'
-# Create the subdirectory if it isn't already there
+# 如果子目录尚不存在则创建一个
if not os.path.exists(today):
os.mkdir(today)
print('Successfully created directory', today)
-# 5. We use the zip command to put the files in a zip archive
+# 5. 我们使用 zip 命令将文件打包成 zip 格式
zip_command = "zip -r {0} {1}".format(target,
' '.join(source))
-# Run the backup
+# 运行备份
print('Zip command is:')
print(zip_command)
print('Running:')
diff --git a/programs/backup_ver4.py b/programs/backup_ver4.py
index c6768333..f3fe811d 100644
--- a/programs/backup_ver4.py
+++ b/programs/backup_ver4.py
@@ -1,54 +1,54 @@
import os
import time
-# 1. The files and directories to be backed up are
-# specified in a list.
-# Example on Windows:
+# 1. 需要备份的文件与目录将被
+# 指定在一个列表中。
+# 例如在 Windows 下：
# source = ['"C:\\My Documents"', 'C:\\Code']
-# Example on Mac OS X and Linux:
+# 又例如在 Mac OS X 与 Linux 下：
source = ['/Users/swa/notes']
-# Notice we had to use double quotes inside the string
-# for names with spaces in it.
+# 在这里要注意到我们必须在字符串中使用双引号
+# 用以括起其中包含空格的名称。
-# 2. The backup must be stored in a
-# main backup directory
-# Example on Windows:
+# 2. 备份文件必须存储在一个
+# 主备份目录中
+# 例如在 Windows 下：
# target_dir = 'E:\\Backup'
-# Example on Mac OS X and Linux:
+# 又例如在 Mac OS X 和 Linux 下：
target_dir = '/Users/swa/backup'
-# Remember to change this to which folder you will be using
+# 要记得将这里的目录地址修改至你将使用的路径
-# Create target directory if it is not present
+# 如果目标目录还不存在，则进行创建
if not os.path.exists(target_dir):
- os.mkdir(target_dir) # make directory
+ os.mkdir(target_dir) # 创建目录
-# 3. The files are backed up into a zip file.
-# 4. The current day is the name of the subdirectory
-# in the main directory.
+# 3. 备份文件将打包压缩成 zip 文件。
+# 4. 将当前日期作为主备份目录下的
+# 子目录名称
today = target_dir + os.sep + time.strftime('%Y%m%d')
-# The current time is the name of the zip archive.
+# 将当前时间作为 zip 文件的文件名
now = time.strftime('%H%M%S')
-# Take a comment from the user to
-# create the name of the zip file
+# 添加一条来自用户的注释以创建
+# zip 文件的文件名
comment = input('Enter a comment --> ')
-# Check if a comment was entered
+# 检查是否有评论键入
if len(comment) == 0:
target = today + os.sep + now + '.zip'
else:
target = today + os.sep + now + '_' + \
comment.replace(' ', '_') + '.zip'
-# Create the subdirectory if it isn't already there
+# 如果子目录尚不存在则创建一个
if not os.path.exists(today):
os.mkdir(today)
print('Successfully created directory', today)
-# 5. We use the zip command to put the files in a zip archive
+# 5. 我们使用 zip 命令将文件打包成 zip 格式
zip_command = 'zip -r {0} {1}'.format(target,
' '.join(source))
-# Run the backup
+# 运行备份
print('Zip command is:')
print(zip_command)
print('Running:')
diff --git a/programs/continue.py b/programs/continue.py
index fe19c3dd..47a34adf 100644
--- a/programs/continue.py
+++ b/programs/continue.py
@@ -6,4 +6,4 @@
print('Too small')
continue
print('Input is of sufficient length')
- # Do other kinds of processing here...
+ # 自此处起继续进行其它任何处理
diff --git a/programs/ds_reference.py b/programs/ds_reference.py
index 34d57c6f..7e76b316 100644
--- a/programs/ds_reference.py
+++ b/programs/ds_reference.py
@@ -1,23 +1,23 @@
print('Simple Assignment')
shoplist = ['apple', 'mango', 'carrot', 'banana']
-# mylist is just another name pointing to the same object!
+# mylist 只是指向同一对象的另一种名称
mylist = shoplist
-# I purchased the first item, so I remove it from the list
+# 我购买了第一项项目，所以我将其从列表中删除
del shoplist[0]
print('shoplist is', shoplist)
print('mylist is', mylist)
-# Notice that both shoplist and mylist both print
-# the same list without the 'apple' confirming that
-# they point to the same object
+# 注意到 shoplist 和 mylist 二者都
+# 打印出了其中都没有 apple 的同样的列表，以此我们确认
+# 它们指向的是同一个对象
print('Copy by making a full slice')
-# Make a copy by doing a full slice
+# 通过生成一份完整的切片制作一份列表的副本
mylist = shoplist[:]
-# Remove first item
+# 删除第一个项目
del mylist[0]
print('shoplist is', shoplist)
print('mylist is', mylist)
-# Notice that now the two lists are different
+# 注意到现在两份列表已出现不同
diff --git a/programs/ds_seq.py b/programs/ds_seq.py
index 52d2d5cf..fec0c24e 100644
--- a/programs/ds_seq.py
+++ b/programs/ds_seq.py
@@ -2,6 +2,7 @@
name = 'swaroop'
# Indexing or 'Subscription' operation #
+# 索引或“下标（Subscription）”操作符 #
print('Item 0 is', shoplist[0])
print('Item 1 is', shoplist[1])
print('Item 2 is', shoplist[2])
@@ -16,7 +17,7 @@
print('Item 1 to -1 is', shoplist[1:-1])
print('Item start to end is', shoplist[:])
-# Slicing on a string #
+# 从某一字符串中切片 #
print('characters 1 to 3 is', name[1:3])
print('characters 2 to end is', name[2:])
print('characters 1 to -1 is', name[1:-1])
diff --git a/programs/ds_str_methods.py b/programs/ds_str_methods.py
index b8d03d5f..b068a123 100644
--- a/programs/ds_str_methods.py
+++ b/programs/ds_str_methods.py
@@ -1,4 +1,4 @@
-# This is a string object
+# 这是一个字符串对象
name = 'Swaroop'
if name.startswith('Swa'):
diff --git a/programs/ds_using_dict.py b/programs/ds_using_dict.py
index 8cae7e28..5477633e 100644
--- a/programs/ds_using_dict.py
+++ b/programs/ds_using_dict.py
@@ -1,4 +1,4 @@
-# 'ab' is short for 'a'ddress'b'ook
+# “ab”是地址（Address）簿（Book）的缩写
ab = {
'Swaroop': 'swaroop@swaroopch.com',
@@ -9,7 +9,7 @@
print("Swaroop's address is", ab['Swaroop'])
-# Deleting a key-value pair
+# 删除一对键值—值配对
del ab['Spammer']
print('\nThere are {} contacts in the address-book\n'.format(len(ab)))
@@ -17,7 +17,7 @@
for name, address in ab.items():
print('Contact {} at {}'.format(name, address))
-# Adding a key-value pair
+# 添加一对键值—值配对
ab['Guido'] = 'guido@python.org'
if 'Guido' in ab:
diff --git a/programs/ds_using_tuple.py b/programs/ds_using_tuple.py
index 2c13a528..09c97745 100644
--- a/programs/ds_using_tuple.py
+++ b/programs/ds_using_tuple.py
@@ -1,7 +1,7 @@
-# I would recommend always using parentheses
-# to indicate start and end of tuple
-# even though parentheses are optional.
-# Explicit is better than implicit.
+# 我会推荐你总是使用括号
+# 来指明元组的开始与结束
+# 尽管括号是一个可选选项。
+# 明了胜过晦涩，显式优于隐式。
zoo = ('python', 'elephant', 'penguin')
print('Number of animals in the zoo is', len(zoo))
diff --git a/programs/exceptions_finally.py b/programs/exceptions_finally.py
index b4d3ffb2..3ca846b7 100644
--- a/programs/exceptions_finally.py
+++ b/programs/exceptions_finally.py
@@ -4,7 +4,7 @@
f = None
try:
f = open("poem.txt")
- # Our usual file-reading idiom
+ # 我们常用的文件阅读风格
while True:
line = f.readline()
if len(line) == 0:
@@ -12,7 +12,7 @@
print(line, end='')
sys.stdout.flush()
print("Press ctrl+c now")
- # To make sure it runs for a while
+ # 为了确保它能运行一段时间
time.sleep(2)
except IOError:
print("Could not find file poem.txt")
diff --git a/programs/exceptions_raise.py b/programs/exceptions_raise.py
index 407ac9da..e8136135 100644
--- a/programs/exceptions_raise.py
+++ b/programs/exceptions_raise.py
@@ -1,5 +1,7 @@
+# encoding=UTF-8
+
class ShortInputException(Exception):
- '''A user-defined exception class.'''
+ '''一个由用户定义的异常类'''
def __init__(self, length, atleast):
Exception.__init__(self)
self.length = length
@@ -9,7 +11,7 @@ def __init__(self, length, atleast):
text = input('Enter something --> ')
if len(text) < 3:
raise ShortInputException(len(text), 3)
- # Other work can continue as usual here
+ # 其他工作能在此处继续正常运行
except EOFError:
print('Why did you do an EOF on me?')
except ShortInputException as ex:
diff --git a/programs/function1.py b/programs/function1.py
index 3351cd08..249d9826 100644
--- a/programs/function1.py
+++ b/programs/function1.py
@@ -1,7 +1,7 @@
def say_hello():
- # block belonging to the function
+ # 该块属于这一函数
print('hello world')
-# End of function
+# 函数结束
-say_hello() # call the function
-say_hello() # call the function again
+say_hello() # 调用函数
+say_hello() # 再次调用函数
diff --git a/programs/function_docstring.py b/programs/function_docstring.py
index 1c9035dc..d4204f41 100644
--- a/programs/function_docstring.py
+++ b/programs/function_docstring.py
@@ -1,8 +1,8 @@
def print_max(x, y):
- '''Prints the maximum of two numbers.
+ '''打印两个数值中的最大数。
- The two values must be integers.'''
- # convert to integers, if possible
+ 这两个数都应该是整数'''
+ # 如果可能，将其转换至整数类型
x = int(x)
y = int(y)
diff --git a/programs/function_docstring.txt b/programs/function_docstring.txt
index 1995f796..b4a25ab2 100644
--- a/programs/function_docstring.txt
+++ b/programs/function_docstring.txt
@@ -1,5 +1,5 @@
$ python function_docstring.py
5 is maximum
-Prints the maximum of two numbers.
+打印两个数值中的最大数。
- The two values must be integers.
+ 这两个数都应该是整数
diff --git a/programs/function_param.py b/programs/function_param.py
index ae9778da..af99dfc5 100644
--- a/programs/function_param.py
+++ b/programs/function_param.py
@@ -6,11 +6,11 @@ def print_max(a, b):
else:
print(b, 'is maximum')
-# directly pass literal values
+# 直接传递字面值
print_max(3, 4)
x = 5
y = 7
-# pass variables as arguments
+# 以参数的形式传递变量
print_max(x, y)
diff --git a/programs/function_varargs.py b/programs/function_varargs.py
index 22db80d2..ce6fceef 100644
--- a/programs/function_varargs.py
+++ b/programs/function_varargs.py
@@ -1,11 +1,11 @@
def total(a=5, *numbers, **phonebook):
print('a', a)
-
- #iterate through all the items in tuple
+
+ #遍历元组中的所有项目
for single_item in numbers:
print('single_item', single_item)
-
- #iterate through all the items in dictionary
+
+ #遍历字典中的所有项目
for first_part, second_part in phonebook.items():
print(first_part,second_part)
diff --git a/programs/if.py b/programs/if.py
index d4cd3e23..3faab483 100644
--- a/programs/if.py
+++ b/programs/if.py
@@ -2,18 +2,18 @@
guess = int(input('Enter an integer : '))
if guess == number:
- # New block starts here
+ # 新块从这里开始
print('Congratulations, you guessed it.')
print('(but you do not win any prizes!)')
- # New block ends here
+ # 新块在这里结束
elif guess < number:
- # Another block
+ # 另一代码块
print('No, it is a little higher than that')
- # You can do whatever you want in a block ...
+ # 你可以在此做任何你希望在该代码块内进行的事情
else:
print('No, it is a little lower than that')
- # you must have guessed > number to reach here
+ # 你必须通过猜测一个大于（>）设置数的数字来到达这里。
print('Done')
-# This last statement is always executed,
-# after the if statement is executed.
+# 这最后一句语句将在
+# if 语句执行完毕后执行。
diff --git a/programs/io_pickle.py b/programs/io_pickle.py
index 1fd345cf..a696794a 100644
--- a/programs/io_pickle.py
+++ b/programs/io_pickle.py
@@ -1,21 +1,21 @@
import pickle
-# The name of the file where we will store the object
+# 我们存储相关对象的文件的名称
shoplistfile = 'shoplist.data'
-# The list of things to buy
+# 需要购买的物品清单
shoplist = ['apple', 'mango', 'carrot']
-# Write to the file
+# 准备写入文件
f = open(shoplistfile, 'wb')
-# Dump the object to a file
+# 转储对象至文件
pickle.dump(shoplist, f)
f.close()
-# Destroy the shoplist variable
+# 清除 shoplist 变量
del shoplist
-# Read back from the storage
+# 重新打开存储文件
f = open(shoplistfile, 'rb')
-# Load the object from the file
+# 从文件中载入对象
storedlist = pickle.load(f)
print(storedlist)
diff --git a/programs/io_using_file.py b/programs/io_using_file.py
index 28a0f857..68bd4d05 100644
--- a/programs/io_using_file.py
+++ b/programs/io_using_file.py
@@ -5,24 +5,24 @@
use Python!
'''
-# Open for 'w'riting
+# 打开文件以编辑（'w'riting）
f = open('poem.txt', 'w')
-# Write text to file
+# 向文件中编写文本
f.write(poem)
-# Close the file
+# 关闭文件
f.close()
-# If no mode is specified,
-# 'r'ead mode is assumed by default
+# 如果没有特别指定，
+# 将假定启用默认的阅读（'r'ead）模式
f = open('poem.txt')
while True:
line = f.readline()
- # Zero length indicates EOF
+ # 零长度指示 EOF
if len(line) == 0:
break
- # The `line` already has a newline
- # at the end of each line
- # since it is reading from a file.
+ # 每行（`line`）的末尾
+ # 都已经有了换行符
+ #因为它是从一个文件中进行读取的
print(line, end='')
-# close the file
+# 关闭文件
f.close()
diff --git a/programs/more_decorator.py b/programs/more_decorator.py
index 52b7f3ed..73be9aa9 100644
--- a/programs/more_decorator.py
+++ b/programs/more_decorator.py
@@ -33,8 +33,8 @@ def save_to_database(arg):
print("This will be automatically retried if exception is thrown.")
global counter
counter += 1
- # This will throw an exception in the first call
- # And will work fine in the second call (i.e. a retry)
+ # 这将在第一次调用时抛出异常
+ # 在第二次运行时将正常工作（也就是重试）
if counter < 2:
raise ValueError(arg)
diff --git a/programs/oop_init.py b/programs/oop_init.py
index 2eb30e11..e41391be 100644
--- a/programs/oop_init.py
+++ b/programs/oop_init.py
@@ -7,5 +7,5 @@ def say_hi(self):
p = Person('Swaroop')
p.say_hi()
-# The previous 2 lines can also be written as
-# Person('Swaroop').say_hi()
+# 前面两行同时也能写作
+# Person('Swaroop').say_hi()
\ No newline at end of file
diff --git a/programs/oop_method.py b/programs/oop_method.py
index e7d5e201..faad700e 100644
--- a/programs/oop_method.py
+++ b/programs/oop_method.py
@@ -4,5 +4,5 @@ def say_hi(self):
p = Person()
p.say_hi()
-# The previous 2 lines can also be written as
-# Person().say_hi()
+# 前面两行同样可以写作
+# Person().say_hi()
\ No newline at end of file
diff --git a/programs/oop_objvar.py b/programs/oop_objvar.py
index 2e6bacbf..bccc837b 100644
--- a/programs/oop_objvar.py
+++ b/programs/oop_objvar.py
@@ -1,20 +1,22 @@
+# coding=UTF-8
+
class Robot:
- """Represents a robot, with a name."""
+ """表示有一个带有名字的机器人。"""
- # A class variable, counting the number of robots
+ # 一个类变量，用来计数机器人的数量
population = 0
def __init__(self, name):
- """Initializes the data."""
+ """初始化数据"""
self.name = name
print("(Initializing {})".format(self.name))
- # When this person is created, the robot
- # adds to the population
+ # 当有人被创建时，机器人
+ # 将会增加人口数量
Robot.population += 1
def die(self):
- """I am dying."""
+ """我挂了。"""
print("{} is being destroyed!".format(self.name))
Robot.population -= 1
@@ -26,14 +28,14 @@ def die(self):
Robot.population))
def say_hi(self):
- """Greeting by the robot.
+ """来自机器人的诚挚问候
- Yeah, they can do that."""
+ 没问题，你做得到。"""
print("Greetings, my masters call me {}.".format(self.name))
@classmethod
def how_many(cls):
- """Prints the current population."""
+ """打印出当前的人口数量"""
print("We have {:d} robots.".format(cls.population))
diff --git a/programs/oop_simplestclass.py b/programs/oop_simplestclass.py
index a49ba831..c60af817 100644
--- a/programs/oop_simplestclass.py
+++ b/programs/oop_simplestclass.py
@@ -1,5 +1,5 @@
class Person:
- pass # An empty block
+ pass # 一个空的代码块
p = Person()
print(p)
diff --git a/programs/oop_subclass.py b/programs/oop_subclass.py
index 780339b0..11e189f4 100644
--- a/programs/oop_subclass.py
+++ b/programs/oop_subclass.py
@@ -1,17 +1,19 @@
+# coding=UTF-8
+
class SchoolMember:
- '''Represents any school member.'''
+ '''代表任何学校里的成员。'''
def __init__(self, name, age):
self.name = name
self.age = age
print('(Initialized SchoolMember: {})'.format(self.name))
def tell(self):
- '''Tell my details.'''
+ '''告诉我有关我的细节。'''
print('Name:"{}" Age:"{}"'.format(self.name, self.age), end=" ")
class Teacher(SchoolMember):
- '''Represents a teacher.'''
+ '''代表一位老师。'''
def __init__(self, name, age, salary):
SchoolMember.__init__(self, name, age)
self.salary = salary
@@ -23,7 +25,7 @@ def tell(self):
class Student(SchoolMember):
- '''Represents a student.'''
+ '''代表一位学生。'''
def __init__(self, name, age, marks):
SchoolMember.__init__(self, name, age)
self.marks = marks
@@ -36,10 +38,10 @@ def tell(self):
t = Teacher('Mrs. Shrividya', 40, 30000)
s = Student('Swaroop', 25, 75)
-# prints a blank line
+# 打印一行空白行
print()
members = [t, s]
for member in members:
- # Works for both Teachers and Students
+ # 对全体师生工作
member.tell()
diff --git a/programs/while.py b/programs/while.py
index 682c15ff..798a92d4 100644
--- a/programs/while.py
+++ b/programs/while.py
@@ -6,7 +6,7 @@
if guess == number:
print('Congratulations, you guessed it.')
- # this causes the while loop to stop
+ # 这将导致 while 循环中止
running = False
elif guess < number:
print('No, it is a little higher than that.')
@@ -14,6 +14,6 @@
print('No, it is a little lower than that.')
else:
print('The while loop is over.')
- # Do anything else you want to do here
+ # 在这里你可以做你想做的任何事
print('Done')
diff --git a/revision_history.md b/revision_history.md
deleted file mode 100644
index bb0e840d..00000000
--- a/revision_history.md
+++ /dev/null
@@ -1,105 +0,0 @@
-# Appendix: History Lesson {#history-lesson}
-
-I first started with Python when I needed to write an installer for software I had written called 'Diamond' so that I could make the installation easy. I had to choose between Python and Perl bindings for the Qt library. I did some research on the web and I came across [an article by Eric S. Raymond](http://www.python.org/about/success/esr/), a famous and respected hacker, where he talked about how Python had become his favorite programming language. I also found out that the PyQt bindings were more mature compared to Perl-Qt. So, I decided that Python was the language for me.
-
-Then, I started searching for a good book on Python. I couldn't find any! I did find some O'Reilly books but they were either too expensive or were more like a reference manual than a guide. So, I settled for the documentation that came with Python. However, it was too brief and small. It did give a good idea about Python but was not complete. I managed with it since I had previous programming experience, but it was unsuitable for newbies.
-
-About six months after my first brush with Python, I installed the (then) latest Red Hat 9.0 Linux and I was playing around with KWord. I got excited about it and suddenly got the idea of writing some stuff on Python. I started writing a few pages but it quickly became 30 pages long. Then, I became serious about making it more useful in a book form. After a _lot_ of rewrites, it has reached a stage where it has become a useful guide to learning the Python language. I consider this book to be my contribution and tribute to the open source community.
-
-This book started out as my personal notes on Python and I still consider it in the same way, although I've taken a lot of effort to make it more palatable to others :)
-
-In the true spirit of open source, I have received lots of constructive suggestions, criticisms and [feedback](./README.md#who-reads-bop) from enthusiastic readers which has helped me improve this book a lot.
-
-## Status Of The Book
-
-The book needs the help of its readers such as yourselves to point out any parts of the book which are not good, not comprehensible or are simply wrong. Please [write to the main author]({{ book.contactUrl }}) or the respective [translators](./translations.md#translations) with your comments and suggestions.
-
-# Appendix: Revision History {#revision-history}
-
-- 4.0
- - 19 Jan 2016
- - Switched back to Python 3
- - Switched back to Markdown, using [GitBook](https://www.gitbook.com) and [Spacemacs](http://spacemacs.org)
-
-- 3.0
- - 31 Mar 2014
- - Rewritten for Python 2 using [AsciiDoc](http://asciidoctor.org/docs/what-is-asciidoc/) and [adoc-mode](https://github.com/sensorflo/adoc-mode/wiki).
-
-- 2.1
- - 03 Aug 2013
- - Rewritten using Markdown and [Jason Blevins' Markdown Mode](http://jblevins.org/projects/markdown-mode/)
-
-- 2.0
- - 20 Oct 2012
- - Rewritten in [Pandoc format](http://johnmacfarlane.net/pandoc/README.html), thanks to my wife who did most of the conversion from the Mediawiki format
- - Simplifying text, removing non-essential sections such as `nonlocal` and metaclasses
-
-- 1.90
- - 04 Sep 2008 and still in progress
- - Revival after a gap of 3.5 years!
- - Rewriting for Python 3.0
- - Rewrite using http://www.mediawiki.org[MediaWiki] (again)
-
-- 1.20
- - 13 Jan 2005
- - Complete rewrite using [Quanta+](https://en.wikipedia.org/wiki/Quanta_Plus) on [Fedora](http://fedoraproject.org/) Core 3 with lot of corrections and updates. Many new examples. Rewrote my DocBook setup from scratch.
-
-- 1.15
- - 28 Mar 2004
- - Minor revisions
-
-- 1.12
- - 16 Mar 2004
- - Additions and corrections
-
-- 1.10
- - 09 Mar 2004
- - More typo corrections, thanks to many enthusiastic and helpful readers.
-
-- 1.00
- - 08 Mar 2004
- - After tremendous feedback and suggestions from readers, I have made significant revisions to the content along with typo corrections.
-
-- 0.99
- - 22 Feb 2004
- - Added a new chapter on modules. Added details about variable number of arguments in functions.
-
-- 0.98
- - 16 Feb 2004
- - Wrote a Python script and CSS stylesheet to improve XHTML output, including a crude-yet-functional lexical analyzer for automatic VIM-like syntax highlighting of the program listings.
-
-- 0.97
- - 13 Feb 2004
- - Another completely rewritten draft, in DocBook XML (again). Book has improved a lot - it is more coherent and readable.
-
-- 0.93
- - 25 Jan 2004
- - Added IDLE talk and more Windows-specific stuff
-
-- 0.92
- - 05 Jan 2004
- - Changes to few examples.
-
-- 0.91
- - 30 Dec 2003
- - Corrected typos. Improvised many topics.
-
-- 0.90
- - 18 Dec 2003
- - Added 2 more chapters. [OpenOffice](https://en.wikipedia.org/wiki/OpenOffice) format with revisions.
-
-- 0.60
- - 21 Nov 2003
- - Fully rewritten and expanded.
-
-- 0.20
- - 20 Nov 2003
- - Corrected some typos and errors.
-
-- 0.15
- - 20 Nov 2003
- - Converted to [DocBook XML](https://en.wikipedia.org/wiki/DocBook) with XEmacs.
-
-- 0.10
- - 14 Nov 2003
- - Initial draft using [KWord](https://en.wikipedia.org/wiki/Kword).
diff --git a/stdlib.md b/stdlib.md
deleted file mode 100644
index 4290d07b..00000000
--- a/stdlib.md
+++ /dev/null
@@ -1,67 +0,0 @@
-# Standard Library {#stdlib}
-
-The Python Standard Library contains a huge number of useful modules and is part of every standard Python installation. It is important to become familiar with the Python Standard Library since many problems can be solved quickly if you are familiar with the range of things that these libraries can do.
-
-We will explore some of the commonly used modules in this library. You can find complete details for all of the modules in the Python Standard Library in the ['Library Reference' section](http://docs.python.org/3/library/) of the documentation that comes with your Python installation.
-
-Let us explore a few useful modules.
-
-> CAUTION: If you find the topics in this chapter too advanced, you may skip this chapter. However, I highly recommend coming back to this chapter when you are more comfortable with programming using Python.
-
-## `sys` module {#sys}
-
-The `sys` module contains system-specific functionality. We have already seen that the `sys.argv` list contains the command-line arguments.
-
-Suppose we want to check the version of the Python software being used, the `sys` module gives us that information.
-
-
-```python
->>> import sys
->>> sys.version_info
-sys.version_info(major=3, minor=5, micro=1, releaselevel='final', serial=0)
->>> sys.version_info.major == 3
-True
-```
-
-**How It Works**
-
-The `sys` module has a `version_info` tuple that gives us the version information. The first entry is the major version. We can pull out this information to use it.
-
-## logging module {#logging}
-
-What if you wanted to have some debugging messages or important messages to be stored somewhere so that you can check whether your program has been running as you would expect it? How do you "store somewhere" these messages? This can be achieved using the `logging` module.
-
-Save as `stdlib_logging.py`:
-
-{% include "./programs/stdlib_logging.py" %}
-
-Output:
-
-{% include "./programs/stdlib_logging.txt" %}
-
-If you do not have the `cat` command, then you can just open the `test.log` file in a text editor.
-
-**How It Works**
-
-We use three modules from the standard library - the `os` module for interacting with the operating system, the `platform` module for information about the platform i.e. the operating system and the `logging` module to *log* information.
-
-First, we check which operating system we are using by checking the string returned by `platform.platform()` (for more information, see `import platform; help(platform)`). If it is Windows, we figure out the home drive, the home folder and the filename where we want to store the information. Putting these three parts together, we get the full location of the file. For other platforms, we need to know just the home folder of the user and we get the full location of the file.
-
-We use the `os.path.join()` function to put these three parts of the location together. The reason to use a special function rather than just adding the strings together is because this function will ensure the full location matches the format expected by the operating system.
-
-We configure the `logging` module to write all the messages in a particular format to the file we have specified.
-
-Finally, we can put messages that are either meant for debugging, information, warning or even critical messages. Once the program has run, we can check this file and we will know what happened in the program, even though no information was displayed to the user running the program.
-
-## Module of the Week Series {#motw}
-
-There is much more to be explored in the standard library such as [debugging](http://docs.python.org/3/library/pdb.html),
-[handling command line options](http://docs.python.org/3/library/argparse.html), [regular expressions](http://docs.python.org/3/library/re.html) and so on.
-
-The best way to further explore the standard library is to read Doug Hellmann's excellent [Python Module of the Week](http://pymotw.com/2/contents.html) series (also available as a [book](http://amzn.com/0321767349)) and reading the [Python documentation](http://docs.python.org/3/).
-
-## Summary
-
-We have explored some of the functionality of many modules in the Python Standard Library. It is highly recommended to browse through the [Python Standard Library documentation](http://docs.python.org/3/library/) to get an idea of all the modules that are available.
-
-Next, we will cover various aspects of Python that will make our tour of Python more _complete_.
diff --git a/styles/pdf.css b/styles/pdf.css
new file mode 100644
index 00000000..4b9a78db
--- /dev/null
+++ b/styles/pdf.css
@@ -0,0 +1 @@
+/* CSS for pdf */
diff --git a/styles/website.css b/styles/website.css
new file mode 100644
index 00000000..6f5520e4
--- /dev/null
+++ b/styles/website.css
@@ -0,0 +1,5 @@
+/* CSS for website */
+
+.book .book-summary, .book .book-body {
+ font-family: "Tsentsiu HG", "Source Han Sans", "Microsoft YaHei UI", "Microsoft Yahei", "PingFang SC", "Lantinghei SC", "Hiragino Sans GB", "WenQuanYi Micro Hei", "WenQuanYi Zen Hei", "Noto Sans CJK SC", "Microsoft JhengHei UI", "Microsoft JhengHei", "PingFang TC", "Lantinghei TC", "Noto Sans CJK TC", "Helvetica Neue", Helvetica, Arial, sans-serif;
+}
diff --git a/translation_howto.md b/translation_howto.md
deleted file mode 100644
index e29615a5..00000000
--- a/translation_howto.md
+++ /dev/null
@@ -1,8 +0,0 @@
-# Translation How-to {#translation-howto}
-
-1. The full source of the book is available from {{ book.sourceUrl }}.
-2. Please [fork the repository](https://help.github.com/articles/fork-a-repo).
-3. Then, fetch the repository to your computer. You need to know how to use [Git](http://www.git-scm.com) to do that.
-4. Read the [GitBook documentation](https://help.gitbook.com), esp. the [Markdown section](https://help.gitbook.com/format/markdown.html).
-5. Start editing the `.md` files to translate to your local language.
-6. [Sign up on GitBook.com](https://www.gitbook.com), create a book and you can see a beautifully rendered website, with links to download PDF, EPUB, etc.
diff --git a/translations.md b/translations.md
deleted file mode 100644
index d75b6a4c..00000000
--- a/translations.md
+++ /dev/null
@@ -1,201 +0,0 @@
-# Translations
-
-There are many translations of the book available in different human languages, thanks to many tireless volunteers!
-
-If you want to help with these translations, please see the list of volunteers and languages below and decide if you want to start a new translation or help in existing translation projects.
-
-If you plan to start a new translation, please read the [Translation how-to](./translation_howto.md#translation-howto).
-
-## Arabic
-
-Below is the link for the Arabic version. Thanks to Ashraf Ali Khalaf for translating the book, you can read the whole book online at or you can download it from [sourceforge.net](http://downloads.sourceforge.net/omlx/byteofpython_arabic.pdf?use_mirror=osdn) for more info see .
-
-## Azerbaijani
-
-Jahangir Shabiyev (c.shabiev@gmail.com) has volunteered to translate the book to Azerbaijani. The translation is in progress at https://www.gitbook.com/book/jahangir-sh/piton-sancmasi
-
-
-## Brazilian Portuguese
-
-There are two translations in various levels of completion and accessibility. The older translation is now missing/lost, and newer translation is incomplete.
-
-Samuel Dias Neto (samuel.arataca@gmail.com) made the first Brazilian Portuguese translation (older translation) of this book when Python was in 2.3.5 version. This is no longer publicly accessible.
-
-[Rodrigo Amaral](http://rodrigoamaral.net) (rodrigoamaral@gmail.com) has volunteered to translate the book to Brazilian Portuguese, (newer translation) which still remains to be completed.
-
-## Catalan
-
-Moises Gomez (moisesgomezgiron@gmail.com) has volunteered to translate the book to Catalan. The translation is in progress.
-
-> Moisès Gómez - I am a developer and also a teacher of programming (normally for people without any previous experience).
->
-> Some time ago I needed to learn how to program in Python, and Swaroop's work was really helpful. Clear, concise, and complete enough. Just what I needed.
->
-> After this experience, I thought some other people in my country could take benefit from it too. But English language can be a barrier.
->
-> So, why not try to translate it? And I did for a previous version of BoP.
->
-> I my country there are two official languages. I selected the Catalan language assuming that others will translate it to the more widespread Spanish.
-
-## Chinese
-
-Translations are available at and .
-
-Juan Shen (orion_val@163.com) has volunteered to translate the book to Chinese.
-
-> I am a postgraduate at Wireless Telecommunication Graduate School, Beijing University of Technology, China PR. My current research interest is on the synchronization, channel estimation and multi-user detection of multicarrier CDMA system. Python is my major programming language for daily simulation and research job, with the help of Python Numeric, actually. I learned Python just half a year before, but as you can see, it's really easy-understanding, easy-to-use and productive. Just as what is ensured in Swaroop's book, 'It's my favorite programming language now'.
->
-> 'A Byte of Python' is my tutorial to learn Python. It's clear and effective to lead you into a world of Python in the shortest time. It's not too long, but efficiently covers almost all important things in Python. I think 'A Byte of Python' should be strongly recommendable for newbies as their first Python tutorial. Just dedicate my translation to the potential millions of Python users in China.
-
-## Chinese Traditional
-
-Fred Lin (gasolin@gmail.com) has volunteered to translate the book to Chinese Traditional.
-
-It is available at .
-
-An exciting feature of this translation is that it also contains the _executable chinese python sources_ side by side with the original python sources.
-
-> Fred Lin - I'm working as a network firmware engineer at Delta Network, and I'm also a contributor of TurboGears web framework.
->
-> As a python evangelist (:-p), I need some material to promote python language. I found 'A Byte of Python' hit the sweet point for both newbies and experienced programmers. 'A Byte of Python' elaborates the python essentials with affordable size.
->
-> The translation are originally based on simplified chinese version, and soon a lot of rewrite were made to fit the current wiki version and the quality of reading.
->
-> The recent chinese traditional version also featured with executable chinese python sources, which are achieved by my new 'zhpy' (python in chinese) project (launch from Aug 07).
->
-> zhpy(pronounce (Z.H.?, or zippy) build a layer upon python to translate or interact with python in chinese(Traditional or Simplified). This project is mainly aimed for education.
-
-## French
-
-Gregory (coulix@ozforces.com.au) has volunteered to translate the book to French.
-
-Gérard Labadie (gerard.labadie@gmail.com) has completed to translate the book to French.
-
-## German
-
-Lutz Horn (lutz.horn@gmx.de), Bernd Hengelein (bernd.hengelein@gmail.com) and Christoph Zwerschke (cito@online.de) have volunteered to translate the book to German.
-
-Their translation is located at
-
-Lutz Horn says:
-
-> I'm 32 years old and have a degree of Mathematics from University of Heidelberg, Germany. Currently I'm working as a software engineer on a publicly funded project to build a web portal for all things related to computer science in Germany.The main language I use as a professional is Java, but I try to do as much as possible with Python behind the scenes. Especially text analysis and conversion is very easy with Python. I'm not very familiar with GUI toolkits, since most of my programming is about web applications, where the user interface is build using Java frameworks like Struts. Currently I try to make more use of the functional programming features of Python and of generators. After taking a short look into Ruby, I was very impressed with the use of blocks in this language. Generally I like the dynamic nature of languages like Python and Ruby since it allows me to do things not possible in more static languages like Java.I've searched for some kind of introduction to programming, suitable to teach a complete non-programmer. I've found the book 'How to Think Like a Computer Scientist: Learning with Python', and 'Dive into Python'. The first is good for beginners but to long to translate. The second is not suitable for beginners. I think 'A Byte of Python' falls nicely between these, since it is not too long, written to the point, and at the same time verbose enough to teach a newbie. Besides this, I like the simple DocBook structure, which makes translating the text a generation the output in various formats a charm.
-
-Bernd Hengelein says:
-
-> Lutz and me are going to do the german translation together. We just started with the intro and preface but we will keep you informed about the progress we make. Ok, now some personal things about me. I am 34 years old and playing with computers since the 1980's, when the "Commodore C64" ruled the nurseries. After studying computer science I started working as a software engineer. Currently I am working in the field of medical imaging for a major german company. Although C++ is the main language I (have to) use for my daily work, I am constantly looking for new things to learn.Last year I fell in love with Python, which is a wonderful language, both for its possibilities and its beauty. I read somewhere in the net about a guy who said that he likes python, because the code looks so beautiful. In my opinion he's absolutly right. At the time I decided to learn python, I noticed that there is very little good documentation in german available. When I came across your book the spontaneous idea of a german translation crossed my mind. Luckily, Lutz had the same idea and we can now divide the work.I am looking forward to a good cooperation!
-
-## Greek
-
-The Greek Ubuntu Community [translated the book in Greek](http://wiki.ubuntu-gr.org/byte-of-python-el), for use in our on-line asynchronous Python lessons that take place in our forums. Contact [@savvasradevic](https://twitter.com/savvasradevic) for more information.
-
-## Indonesian
-
-Daniel (daniel.mirror@gmail.com) is translating the book to Indonesian at .
-
-Wisnu Priyambodo (cibermen@gmail.com) also has volunteered to translate the book to Indonesian.
-
-Also, Bagus Aji Santoso (baguzzzaji@gmail.com) has volunteered.
-
-## Italian (first)
-
-Enrico Morelli (mr.mlucci@gmail.com) and Massimo Lucci (morelli@cerm.unifi.it) have volunteered to translate the book to Italian.
-
-The Italian translation is present at .
-
-> _Massimo Lucci and Enrico Morelli_ - we are working at the University of Florence (Italy) - Chemistry Department. I (Massimo) as service engineer and system administrator for Nuclear Magnetic Resonance Spectrometers; Enrico as service engineer and system administrator for our CED and parallel / clustered systems. We are programming on python since about seven years, we had experience working with Linux platforms since ten years. In Italy we are responsible and administrator for www.gentoo.it web site for Gentoo/Linux distrubution and www.nmr.it (now under construction) for Nuclear Magnetic Resonance applications and Congress Organization and Managements.That's all! We are impressed by the smart language used on your Book and we think this is essential for approaching the Python to new users (we are thinking about hundred of students and researcher working on our labs).
-
-## Italian (second)
-
-An Italian translation has been created by
-[Calvina Bice](http://besthcgdropswebsite.com/translate) & colleagues at .
-
-## Japanese
-
-Shunro Dozono (dozono@gmail.com) is translating the book to Japanese.
-
-## Korean
-
-Jeongbin Park (pjb7687@gmail.com) has translated the book to Korean -
-
-> I am Jeongbin Park, currently working as a Biophysics & Bioinformatics researcher in Korea.
->
-> A year ago, I was looking for a good tutorial/guide for Python to introduce it to my colleagues, because using Python in such research fields is becoming inevitable due to the user base is growing more and more.
->
-> But at that time only few Python books are available in Korean, so I decided to translate your ebook because it looks like one of the best guides that I have ever read!
->
-> Currently, the book is almost completely translated in Korean, except some of the text in introduction chapter and the appendixes.
->
-> Thank you again for writing such a good guide!
-
-## Mongolian
-
-Ariunsanaa Tunjin (luftballons2010@gmail.com) has volunteered to translate the book to Mongolian.
-
-_Update on Nov 22, 2009_ : Ariunsanaa is on the verge of completing the translation.
-
-## Norwegian (bokmål)
-
-Eirik Vågeskar is a high school student at [Sandvika videregående skole](http://no.wikipedia.org/wiki/Sandvika_videreg%C3%A5ende_skole) in Norway, a [blogger](http://forbedre.blogspot.com/) and currently translating the book to Norwegian (bokmål).
-
-> _Eirik Vågeskar_: I have always wanted to program, but because I speak a small language, the learning process was much harder. Most tutorials and books are written in very technical English, so most high school graduates will not even have the vocabulary to understand what the tutorial is about. When I discovered this book, all my problems were solved. "A Byte of Python" used simple non-technical language to explain a programming language that is just as simple, and these two things make learning Python fun. After reading half of the book, I decided that the book was worth translating. I hope the translation will help people who have found themself in the same situation as me (especially young people), and maybe help spread interest for the language among people with less technical knowledge.
-
-## Polish
-
-Dominik Kozaczko (dominik@kozaczko.info) has volunteered to translate the book to Polish. Translation is in progress and it's main page is available here: [Ukąś Pythona](http://python.edu.pl/byteofpython/).
-
-_Update_ : The translation is complete and ready as of Oct 2, 2009. Thanks to Dominik, his two students and their friend for their time and effort!
-
-> _Dominik Kozaczko_ - I'm a Computer Science and Information Technology teacher.
-
-## Portuguese
-
-Fidel Viegas (fidel.viegas@gmail.com) has volunteered to translate the book to Portuguese.
-
-## Romanian
-
-Paul-Sebastian Manole (brokenthorn@gmail.com) has volunteered to translate this book to Romanian.
-
-> _Paul-Sebastian Manole_ - I'm a second year Computer Science student at Spiru Haret University, here in Romania. I'm more of a self-taught programmer and decided to learn a new language, Python. The web told me there was no better way to do so but read ''A Byte of Python''. That's how popular this book is (congratulations to the author for writing such an easy to read book). I started liking Python so I decided to help translate the latest version of Swaroop's book in Romanian. Although I could be the one with the first initiative, I'm just one volunteer so if you can help, please join me.
-
-## Russian
-
-Vladimir Smolyar (v_2e@ukr.net) has completed a Russian translation at .
-
-## Ukranian
-
-Averkiev Andrey (averkiyev@ukr.net) has volunteered to translate the book to Russian, and perhaps Ukranian (time permitting).
-
-## Serbian
-
-"BugSpice" (amortizerka@gmail.com) has completed a Serbian translation:
-
-> This download link is no longer accessible.
-
-More details at .
-
-## Slovak
-
-Albertio Ward (albertioward@gmail.com) has translated the book to Slovak at :
-
-> We are a non-profit organization called "Translation for education". We represent a group of people, mainly students and professors, of the Slavonic University. Here are students from different departments: linguistics, chemistry, biology, etc. We try to find interesting publications on the Internet that can be relevant for us and our university colleagues. Sometimes we find articles by ourselves; other times our professors help us choose the material for translation. After obtaining permission from authors we translate articles and post them in our blog which is available and accessible to our colleagues and friends. These translated publications often help students in their daily study routine.
-
-## Spanish
-
-Alfonso de la Guarda Reyes (alfonsodg@ictechperu.net), Gustavo Echeverria (gustavo.echeverria@gmail.com), David Crespo Arroyo (davidcrespoarroyo@hotmail.com) and Cristian Bermudez Serna (crisbermud@hotmail.com) have volunteered to translate the book to Spanish.
-
-Gustavo Echeverria says:
-
-> I work as a software engineer in Argentina. I use mostly C# and .Net technologies at work but strictly Python or Ruby in my personal projects. I knew Python many years ago and I got stuck inmediately. Not so long after knowing Python I discovered this book and it helped me to learn the language. Then I volunteered to translate the book to Spanish. Now, after receiving some requests, I've begun to translate "A Byte of Python" with the help of Maximiliano Soler.
-
-Cristian Bermudez Serna says:
-
-> I am student of Telecommunications engineering at the University of Antioquia (Colombia). Months ago, i started to learn Python and found this wonderful book, so i volunteered to get the Spanish translation.
-
-## Swedish
-
-Mikael Jacobsson (leochingkwake@gmail.com) has volunteered to translate the book to Swedish.
-
-## Turkish
-
-Türker SEZER (tsezer@btturk.net) and Bugra Cakir (bugracakir@gmail.com) have volunteered to translate the book to Turkish. "Where is Turkish version? Bitse de okusak."
diff --git a/what_next.md b/what_next.md
deleted file mode 100644
index fd16c3b4..00000000
--- a/what_next.md
+++ /dev/null
@@ -1,148 +0,0 @@
-# What Next
-
-If you have read this book thoroughly till now and practiced writing a lot of programs, then you must have become comfortable and familiar with Python. You have probably created some Python programs to try out stuff and to exercise your Python skills as well. If you have not done it already, you should. The question now is 'What Next?'.
-
-I would suggest that you tackle this problem:
-
-> Create your own command-line *address-book* program using which you can browse, add, modify, delete or search for your contacts such as friends, family and colleagues and their information such as email address and/or phone number. Details must be stored for later retrieval.
-
-This is fairly easy if you think about it in terms of all the various stuff that we have come across till now. If you still want directions on how to proceed, then here's a hint [^1].
-
-Once you are able to do this, you can claim to be a Python programmer. Now, immediately [send me an email]({{ book.contactUrl }}) thanking me for this great book ;-). This step is optional but recommended. Also, please consider [buying a printed copy]({{ book.buyBookUrl }}) to support the continued development of this book.
-
-If you found that program easy, here's another one:
-
-> Implement the [replace command](http://unixhelp.ed.ac.uk/CGI/man-cgi?replace). This command will replace one string with another in the list of files provided.
-
-The replace command can be as simple or as sophisticated as you wish, from simple string substitution to looking for patterns (regular expressions).
-
-## Next Projects
-
-If you found above programs easy to create, then look at this comprehensive list of projects and try writing your own programs: https://github.com/thekarangoel/Projects#numbers (the same list is also at [Martyr2's Mega Project List](http://www.dreamincode.net/forums/topic/78802-martyr2s-mega-project-ideas-list/)).
-
-Also see:
-
-- [Exercises for Programmers: 57 Challenges to Develop Your Coding Skills](https://pragprog.com/book/bhwb/exercises-for-programmers)
-- [Intermediate Python Projects](https://openhatch.org/wiki/Intermediate_Python_Workshop/Projects).
-
-## Example Code
-
-The best way to learn a programming language is to write a lot of code and read a lot of code:
-
-- [Python Cookbook](http://code.activestate.com/recipes/langs/python/) is an extremely valuable collection of recipes or tips on how to solve certain kinds of problems using Python. This is a must-read for every Python user.
-- [Python Module of the Week](http://pymotw.com/2/contents.html) is another excellent must-read guide to the [Standard Library](./stdlib.md#stdlib).
-
-## Advice
-
-- [The Hitchhiker's Guide to Python!](http://docs.python-guide.org/en/latest/)
-- [The Elements of Python Style](https://github.com/amontalenti/elements-of-python-style)
-- [Python Big Picture](http://slott-softwarearchitect.blogspot.ca/2013/06/python-big-picture-whats-roadmap.html)
-- ["Writing Idiomatic Python" ebook](http://www.jeffknupp.com/writing-idiomatic-python-ebook/) (paid)
-
-## Videos
-
-- [Full Stack Web Development with Flask](https://github.com/realpython/discover-flask)
-- [PyVideo](http://www.pyvideo.org)
-
-## Questions and Answers
-
-- [Official Python Dos and Don'ts](http://docs.python.org/3/howto/doanddont.html)
-- [Official Python FAQ](http://www.python.org/doc/faq/general/)
-- [Norvig's list of Infrequently Asked Questions](http://norvig.com/python-iaq.html)
-- [Python Interview Q & A](http://dev.fyicenter.com/Interview-Questions/Python/index.html)
-- [StackOverflow questions tagged with python](http://stackoverflow.com/questions/tagged/python)
-
-## Tutorials
-
-- [Hidden features of Python](http://stackoverflow.com/q/101268/4869)
-- [What's the one code snippet/python trick/etc did you wish you knew when you learned python?](http://www.reddit.com/r/Python/comments/19dir2/whats_the_one_code_snippetpython_tricketc_did_you/)
-- [Awaretek's comprehensive list of Python tutorials](http://www.awaretek.com/tutorials.html)
-
-## Discussion
-
-If you are stuck with a Python problem, and don't know whom to ask, then the [python-tutor list](http://mail.python.org/mailman/listinfo/tutor) is the best place to ask your question.
-
-Make sure you do your homework by trying to solving the problem yourself first and [ask smart questions](http://catb.org/~esr/faqs/smart-questions.html).
-
-## News
-
-If you want to learn what is the latest in the world of Python, then follow the [Official Python Planet](http://planet.python.org).
-
-## Installing libraries
-
-There are a huge number of open source libraries at the [Python Package Index](http://pypi.python.org/pypi) which you can use in your own programs.
-
-To install and use these libraries, you can use [pip](http://www.pip-installer.org/en/latest/).
-
-## Creating a Website
-
-Learn [Flask](http://flask.pocoo.org) to create your own website. Some resources to get started:
-
-- [Flask Official Quickstart](http://flask.pocoo.org/docs/quickstart/)
-- [The Flask Mega-Tutorial](http://blog.miguelgrinberg.com/post/the-flask-mega-tutorial-part-i-hello-world)
-- [Example Flask Projects](https://github.com/mitsuhiko/flask/tree/master/examples)
-
-## Graphical Software
-
-Suppose you want to create your own graphical programs using Python. This can be done using a GUI (Graphical User Interface) library with their Python bindings. Bindings are what allow you to write programs in Python and use the libraries which are themselves written in C or C++ or other languages.
-
-There are lots of choices for GUI using Python:
-
-- Kivy
- - http://kivy.org
-
-- PyGTK
- - This is the Python binding for the GTK+ toolkit which is the foundation upon which GNOME is built. GTK+ has many quirks in usage but once you become comfortable, you can create GUI apps fast. The Glade graphical interface designer is indispensable. The documentation is yet to improve. GTK+ works well on GNU/Linux but its port to Windows is incomplete. You can create both free as well as proprietary software using GTK+. To get started, read the [PyGTK tutorial](http://www.pygtk.org/tutorial.html).
-
-- PyQt
- - This is the Python binding for the Qt toolkit which is the foundation upon which the KDE is built. Qt is extremely easy to use and very powerful especially due to the Qt Designer and the amazing Qt documentation. PyQt is free if you want to create open source (GPL'ed) software and you need to buy it if you want to create proprietary closed source software. Starting with Qt 4.5 you can use it to create non-GPL software as well. To get started, read about [PySide](http://qt-project.org/wiki/PySide).
-
-- wxPython
- - This is the Python bindings for the wxWidgets toolkit. wxPython has a learning curve associated with it. However, it is very portable and runs on GNU/Linux, Windows, Mac and even embedded platforms. There are many IDEs available for wxPython which include GUI designers as well such as [SPE (Stani's Python Editor)](http://spe.pycs.net/) and the [wxGlade](http://wxglade.sourceforge.net/) GUI builder. You can create free as well as proprietary software using wxPython. To get started, read the [wxPython tutorial](http://zetcode.com/wxpython/).
-
-### Summary of GUI Tools
-
-For more choices, see the [GuiProgramming wiki page at the official python website](http://www.python.org/cgi-bin/moinmoin/GuiProgramming).
-
-Unfortunately, there is no one standard GUI tool for Python. I suggest that you choose one of the above tools depending on your situation. The first factor is whether you are willing to pay to use any of the GUI tools. The second factor is whether you want the program to run only on Windows or on Mac and GNU/Linux or all of them. The third factor, if GNU/Linux is a chosen platform, is whether you are a KDE or GNOME user on GNU/Linux.
-
-For a more detailed and comprehensive analysis, see Page 26 of the ['The Python Papers, Volume 3, Issue 1' (PDF)](http://archive.pythonpapers.org/ThePythonPapersVolume3Issue1.pdf).
-
-## Various Implementations
-
-There are usually two parts a programming language - the language and the software. A language is _how_ you write something. The software is _what_ actually runs our programs.
-
-We have been using the _CPython_ software to run our programs. It is referred to as CPython because it is written in the C language and is the _Classical Python interpreter_.
-
-There are also other software that can run your Python programs:
-
-- [Jython](http://www.jython.org)
- - A Python implementation that runs on the Java platform. This means you can use Java libraries and classes from within Python language and vice-versa.
-
-- [IronPython](http://www.codeplex.com/Wiki/View.aspx?ProjectName=IronPython)
- - A Python implementation that runs on the .NET platform. This means you can use .NET libraries and classes from within Python language and vice-versa.
-
-- [PyPy](http://codespeak.net/pypy/dist/pypy/doc/home.html)
- - A Python implementation written in Python! This is a research project to make it fast and easy to improve the interpreter since the interpreter itself is written in a dynamic language (as opposed to static languages such as C, Java or C# in the above three implementations)
-
-There are also others such as [CLPython](http://common-lisp.net/project/clpython/) - a Python implementation written in Common Lisp and [Brython](http://brython.info/) which is an implementation on top of a JavaScript interpreter which could mean that you can use Python (instead of JavaScript) to write your web-browser ("Ajax") programs.
-
-Each of these implementations have their specialized areas where they are useful.
-
-## Functional Programming (for advanced readers) {#functional-programming}
-
-When you start writing larger programs, you should definitely learn more about a functional approach to programming as opposed to the class-based approach to programming that we learned in the [object-oriented programming chapter](./oop.md#oop):
-
-- [Functional Programming Howto by A.M. Kuchling](http://docs.python.org/3/howto/functional.html)
-- [Functional programming chapter in 'Dive Into Python' book](http://www.diveintopython.net/functional_programming/index.html)
-- [Functional Programming with Python presentation](http://ua.pycon.org/static/talks/kachayev/index.html)
-- [Funcy library](https://github.com/Suor/funcy)
-- [PyToolz library](http://toolz.readthedocs.org/en/latest/)
-
-## Summary
-
-We have now come to the end of this book but, as they say, this is the _the beginning of the end_!. You are now an avid Python user and you are no doubt ready to solve many problems using Python. You can start automating your computer to do all kinds of previously unimaginable things or write your own games and much much more. So, get started!
-
----
-
-[^1]: Create a class to represent the person's information. Use a dictionary to store person objects with their name as the key. Use the pickle module to store the objects persistently on your hard disk. Use the dictionary built-in methods to add, delete and modify the persons.