As someone who does most of their professional development in Python, I’ve been eagerly waiting for something like Mypy, but my experience with it has been really disappointing and frustrating compared to languages like Go. Mypy mostly seems immature, buggy, and completely unergonomic (typing support was shoehorned into the syntax so most things chafe—declaring a type variable or a callable that takes args and kwargs). Python needs a better static typing story in order to be a productive language in medium-to-large-sized projects.