I’ve used #pytype for >year now and recently ran into latest release on 3.11 not being able to handle a simple signature of a function returning a closure. Finally I looked into what other type checkers are popular today and discovered #mypy . With –strict it did a great job. Go #dropbox ! I guess this happens when a big tech company fires their py team ( #pytype ).

from collections.abc import Callable

def gen_agent(num_agents: int=OPTS.num_agents) -> Callable[[], int]: