Addresses review of #11630

[sobolevn]

Refs #11630

[hauntsaninja]

Thanks, but I think is_operator needs to be True... See #11637

[sobolevn]

@hauntsaninja with is_operator=True this condition does not work: https://github.com/python/mypy/blob/master/mypy/checkmember.py#L385-L386

I think that I might be confused by how __getattr__ works with __call__ here 🤔

[hauntsaninja]

I might be confused too :-) See #11630 (comment) for what I'm looking at

[sobolevn]

TIL that __getattr__ is not called when we use this code:

class D:
    def __getattr__(self, attr: str) -> DCall:
        if attr == "__call__":
            return lambda *a, **kw: print(a, kw)
        raise AttributeError

D().__call__('a')  # called
D()('a')  # not called

So, my assumption of allowing classes with __getattr__ to be treated as callables - is not correct. I will update this PR appropriately.

Thanks!