I clicked through on this and browsed a few directories, none of which seemed likely. I do not see any `.py` files aside from an empty `__init__.py` and the `setup.py`. Are you sure a beginner just learning Python should see this?
The main codebase is in `inbox/`, with launcher scripts and tools in `bin/`.
(Might not be totally obvious, because the package namespace is called `inbox/` for legacy reasons.)
If a beginner wants to see real production code, rather than toy examples, I think it's inevitable that there will be some points of confusion. Part of the learning process is diving in and exploring and being okay with not totally understanding everything that's going on. :)