Mypy and type checking for dynamically generated and imported schemas

[sneakers-the-rat]

importing from yaml is cool, but it's not so cool if you don't get any type hinting.

is this possible with mypy/other type checkers? taking notes.

• https://mypy.readthedocs.io/en/stable/extending_mypy.html - get_dynamic_class_hook might be what we want
• or maybe get_additional_deps() to just import the module from the __pycache__ directory - the whole reason we put it there in the first place is to make it unambiguous when it is generated, but we do actually import from there