Gets the configured broker type
    :param list_key: optional queue name
    :type list_key: str
    :return:

def get_broker(list_key=Conf.PREFIX):
    """
    Gets the configured broker type
    :param list_key: optional queue name
    :type list_key: str
    :return:
    """
    # custom
    if Conf.BROKER_CLASS:
        module, func = Conf.BROKER_CLASS.rsplit('.', 1)
        m = importlib.import_module(module)
        broker = getattr(m, func)
        return broker(list_key=list_key)
    # disque
    elif Conf.DISQUE_NODES:
        from django_q.brokers import disque
        return disque.Disque(list_key=list_key)
    # Iron MQ
    elif Conf.IRON_MQ:
        from django_q.brokers import ironmq
        return ironmq.IronMQBroker(list_key=list_key)
    # SQS
    elif Conf.SQS:
        from django_q.brokers import aws_sqs
        return aws_sqs.Sqs(list_key=list_key)
    # ORM
    elif Conf.ORM:
        from django_q.brokers import orm
        return orm.ORM(list_key=list_key)
    # Mongo
    elif Conf.MONGO:
        from django_q.brokers import mongo
        return mongo.Mongo(list_key=list_key)
    # default to redis
    else:
        from django_q.brokers import redis_broker
        return redis_broker.Redis(list_key=list_key)