Reading the source code of established open source projects is a great way to learn techniques in your programming language of choice.
I read through and lightly annotated the
sessions.py file of the Requests
library. The source code can be viewed directly here. If you are a beginner
or intermediate Python programmer, or if you are just curious to see what the
source code of a major open source project looks like, you may find value in the
notes I made.