Invis
Invis is an invisible framework which purpose is to enforce type checking of both builtins as well as user defined types at runtime. It is distributed as a single file with no extra dependencies other than the Python Standard Library (>= 3.7).
To install: pip install invis
A comprehensive tutorial on how to use the framework can be found here
A discussion about the project, held on reddit's algotrading subforum, can be found here