Shared via mypy Playground

main.py

from typing import TypeVar, Generic

T = TypeVar("T")

class W(Generic[T]):
   def managed(self) -> T:
       raise NotImplementedError

class MW(Generic[T]):
    def __init__(self, w: T) -> None:
        ...

class A(Generic[T], W[AM[T]]): pass

class AM(Generic[T], MW[A[T]]):
    pass