feat: add interface files with mypy information to aid with type checking

[EpsilonPrime]

No description provided.

[gforsyth]

this seems like a reasonable change. I think you also need to add an empty file called py.typed in the src/ directory to inform downstream projects that type information is available.

[EpsilonPrime]

this seems like a reasonable change. I think you also need to add an empty file called py.typed in the src/ directory to inform downstream projects that type information is available.

Having the type information and enforcing it seem like two different levels. I do want to add py.typed but I believe that should be done in a followup PR especially as it has the possibility to affect downstream packages.