def meta_create(self, cls, props):
        db = self.db  # the session
        ...

    def meta_create_linked(self, base, cls, **props):
        pass

    def meta_edit(self, id, **props):
        pass

    def meta_delete(self, id):
        pass

    def meta_link_add(self, base, node):
        pass

    def meta_link_del(self, base, node):
        pass