bad-mcs-method-argument / C0203

Message emitted:

Metaclass method %s should have %s as first argument

Description:

Used when a metaclass method has a first argument named differently than the value specified in valid-classmethod-first-arg option (default to "cls"), recommended to easily differentiate them from regular instance methods.

Problematic code:

class Meta(type):
    def func(some):  # [bad-mcs-method-argument]
        pass

Correct code:

class Meta(type):
    def func(cls):
        pass

Created by the classes checker.