metaarg.py

class MetaSpam(type):
    def __new__(cls, name, bases, ns, *, metaarg=92):
        print("new", metaarg)
        return super().__new__(cls, name, bases, ns)

    def __init__(self, name, bases, ns, *, metaarg=92):
        print("init", metaarg)
        super().__init__(name, bases, ns)

class A(metaclass=MetaSpam, metaarg="WUT?"):
    pass

a = A()