Comment by IshKebab

Sure but nobody ever writes tests that are as comprehensive at checking the basic types of stuff as simply adding static type hints (which is very easy if you start with them).

How many times have you seen a NoneType error or a KeyError? It's probably the most common class of bugs in Python and there's an easy way to eliminate it. And as a nice side effect your code is way easier to understand, navigate and edit.

I still sometimes have to give up and use Any in Python, partly because half the Python community haven't realised their mistake yet. But that's fine. It's still way better.