code: function pop($queue = null)
      {
          if ( null === $j = parent::pop($queue) && !empty($this->queues) )
              // Set Default Once The Queue Is Empty
              $this->setDefaultQueues($this->_defaults);
  
          else return $j;
  
  
          // Try To Pop Again; With defaults queue values ...
          return parent::pop($queue);
      }
docs: Pop From Queue
  
  note: when you pop a message from queue you have to
  release it when worker done with it.
  
  
  @param string $queue
  
  @return iPayloadQueued|null
  @throws exIOError