bad-mcs-method-argument / C0203#
Metaclass method %s should have %s as first argument
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.
class Meta(type): def func(some): # [bad-mcs-method-argument] pass
class Meta(type): def func(cls): pass
Created by the classes checker.