Add a suggestion to CONTRIBUTING.md (#5205)

JelleZijlstra · hauntsaninja · web-flow · commit fc0db5f2b6d7 · 2021-04-11T06:50:08.000-07:00
Co-authored-by: Shantanu &lt;12621235+hauntsaninja@users.noreply.github.com&gt;
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
@@ -339,6 +339,9 @@ harmless.  This is a strictly better compromise than using the latter
 two forms, which would generate false positive errors for correct use
 under Python 3.7.4.
 
+When your stub contains if statements for different Python versions,
+always put the code for the most recent Python version first.
+
 Note: in its current implementation, typeshed cannot contain stubs for
 multiple versions of the same third-party library.  Prefer to generate
 stubs for the latest version released on PyPI at the time of your
