Add Package Stubs

**Is your feature request related to a problem? Please describe.**
Not a problem- but mypy complains that it can't find the stubs/types.

**Describe the solution you'd like**
Add stubs directly to the project (vs. a separate package). Can usually be done with mypy's stubgen.

**Describe alternatives you've considered**
N/A

**Additional context**
N/A
