code: def BROKER_TYPE(self):
          
  
          broker_type = get('BROKER_TYPE', DEFAULT_BROKER_TYPE)
          if broker_type not in SUPPORTED_BROKER_TYPES:
              log.warn("Specified BROKER_TYPE {} not supported. Backing to default {}".format(
                  broker_type, DEFAULT_BROKER_TYPE))
              return DEFAULT_BROKER_TYPE
          else:
              return broker_type
docs: Custom setting allowing switch between rabbitmq, redis