Hi.
Are the maintainers open to accepting the addition of type annotations to this project? I am willing to do the work that's needed.
If the answer is yes, a few extra questions:

1. Should those be in-code or as separate .pyi files?
2. Since the project supports 3.7+, would you accept the from __future__ import annotations import way (newer, nicer typing syntax) or should I go with "classic" type classes from the typing module?
3. Should I add type-checking as part of the CI/tox task?