Add comments and type hints to python code

The python code current has nearly zero comments, which makes it difficult for people to figure out what the code is actually doing. Having comments would make it easier for people who are less familar with python and this specific codebase to contribute. Type hints would also be a useful addition for similar reasons.

No files, tests, or entry points are identified in the issue. Begin by locating the Python code in the repository and determining its scope; done means the relevant Python code has useful comments and type hints that make its behavior easier for contributors to understand.

Written by the indexing model from the issue text.