code: def enqueue(self, item, queue=None):
          
          if queue is None:
              queue = self.queue
          is_enqueue_item = True
  
          if self.invalid_key_list is not None:
              for entry in self.invalid_key_list:
                  if entry in item.data['key']:
                      is_enqueue_item = False
                      log_message = (
                          '{key} is filtered by "invalid_key_list".'
                          ''.format(key=item.data['key'],
                                    plugin=__name__)
                      )
                      self.logger.debug(log_message)
                      break
  
          if is_enqueue_item:
              try:
                  queue.put(item, block=False)
                  return True
              except Full:
                  self.logger.error('Blackbird item Queue is Full!!!')
                  return False
  
          else:
              return False
docs: Enqueue items.
          If you define "self.filter" (sequence),
          this method put the item to queue after filtering.
          "self.filter" operates as blacklist.
  
          This method expects that
          "item" argument has dict type "data" attribute.