from pathlib import Path
data_folder = Path("source_data/text_files/")
file_to_open = data_folder / "raw_data.txt"

# It also works concatenating multiple strings on the fly:
>>> a_string = "path/to/something"
>>> a_path = Path(a_string+"/new/directory/type")
PosixPath('path/to/something/new/directory/type')

# and adding a str to a Path
>>> a_path / "new/string/path"
PosixPath('path/to/something/new/directory/type/new/string/path')

import os
data_folder = os.path.join("source_data", "text_files")
file_to_open = os.path.join(data_folder, "raw_data.txt")

# This also works concatenating a string and a pathlib Path
>>> ab = Path("test/one")
>>> os.path.join(ab,"other/test/")
'test/one/other/test/'