Adding type hints

[obriente]

To get this codebase up to standard, we need to add type hints. At the very least, perhaps we should start insisting that all new code has type hints added, but moreover we need to add typing to the code that currently exists.

This is a pretty large project, but luckily it can be done incrementally - I believe at this point it's a stretch goal for v1, if anyone wants to help it would be much appreciated. It's also a good first project for anyone wanting to understand openfermion, as it doesn't require much understanding of the codebase --- we've been pretty consistent in adding type hints to docstrings.

[jitendrs]

HI @obriente I will be happy to help you out with this issue. let me know how I can start.

[obriente]

Hi @jitendrs - I guess it's probably best to start adding hints to some of the higher level locations - say transforms, hamiltonians, and circuits. Basically just add the hints, make sure they don't create circular imports, and then create a PR and I can review it. Thanks!

[jitendrs]

@obriente Thanks. let me start looking at the code.

[A1eph0]

Hi! I am new to OpenFermion. If no one is currently working on this, I would like to take this up.

[babbush]

@A1eph0 sure! That would be great!