from warnings import deprecated


@deprecated("MyMeta will go away soon")
class MyMeta(type):
    def __new__(mcs, name, bases, attrs, cls=None):
        return super().__new__(mcs, name, bases, attrs)


class Foo(metaclass=MyMeta, cls='haha'):
    pass

$ python3 test.py
Traceback (most recent call last):
  File "/Users/PanXuehai/Projects/cpython/test.py", line 10, in <module>
    class Foo(metaclass=MyMeta, cls='haha'):
        pass
TypeError: MyMeta.__new__() got multiple values for argument 'cls'