Add more docstrings to python methods

[jonespm]

Something I'd like to get better about (again) is using docstrings. I used these consistently in Java and more consistently in MyLA but I think not as much here. There's an extension for this but I'm not sure the format. to use. Sphinx and "one-line Sphnix" seem the most popular but Google looks easiest to read, though taking up more space.

We can go back and do this on another issue too, or start with this one!

Originally posted by @jonespm in #167 (comment)