[Python-ideas] Re: len(Enum) should raise TypeError

mypy does not detect this as a problem because EnumMeta has a `.__len__` method https://github.com/python/typeshed/blob/60939b00afede13feeec3cee6f6dfe6eb2df... what would the type hints look like if len(Enum) failed but class Foo(Enum): pass len(Foo) succeeds?