liskov.behave_as

        def behave_as(*bases):
    substitute_bases = _load_bases(bases)

    class Liskov(type):
        constraints = tuple()
        def __new__(cls, name, bases, attrs):
            new_bases = _remove_bases_behaviours(substitute_bases, cls.constraints)
            return type.__new__(cls, name, new_bases + bases, attrs)

        @classmethod
        def except_for(cls, *behaviours):
            cls.constraints = behaviours
            return cls

    return Liskov