stub.py

from collections import UserDict

class Stub(UserDict):

    def __getattr__(self, name):
        return self

    def __getitem__(self, key):
        item = getattr(self, key, self)
        try:
            item = super().__getitem__(key)
        except KeyError:
            pass
        return item

    def __call__(self, *args, **kwargs):
        return self