We allow dropping argument annotations, but not return annotations in static Python

[DinoV]

This code results in a compile time error:

class C:
    def f(self, a: int) -> int: pass

class D(C):
    def f(self, a: int): pass

But this code does not:

class C:
    def f(self, a: int) -> int: pass

class D(C):
    def f(self, a) -> int: pass

We should consistently require matching annotations.

[DinoV]

Actually this is fine, we are allowing a to take a less specific type, and disallowing returning a less specific type.