Mypy, originally developed at Dropbox to optimize its own internal codebase, was arguably the first static type checking system for Python ... add the attribute _HAS_DYNAMIC_ATTRIBUTES = True ...

[See "Introducing Mypy, an Experimental Optional Static Type Checker for Python" and "Python's Mypy—Advanced Usage".] For people (like me) who have enjoyed dynamic languages for a long time, Mypy ...

Guido van Rossum, the creator of the hugely popular Python programming language ... as well as the open source Mypy static type checker that Dropbox develops to manage Python code at scale.