How to use the pykka.ActorRegistry.get_by_class_name function in pykka

def test_actors_may_be_looked_up_by_class_name(
    actor_a_class, a_actor_refs, b_actor_refs
):
    result = ActorRegistry.get_by_class_name('ActorA')

    for a_actor in a_actor_refs:
        assert a_actor in result
    for b_actor in b_actor_refs:
        assert b_actor not in result

def getTagActor(self):
        return pykka.ActorRegistry.get_by_class_name("NfcActor")[0].proxy()

def get_actor(self, name):
        fsm = pykka.ActorRegistry.get_by_class_name(name)
        if fsm:
            return fsm[0].proxy()
        logger.critical("Actor %s not found!!!" % name)
        return None