code: public function removeUnreceivedMessage($index)
      {
          if ($index < 0 || $index >= count($this->unreceivedMessages)) {
              throw new Exception\OutOfRangeException('The "un-received" message index must be between 0 (inclusive) and the length of the queue (exclusive)');
          }
          array_splice($this->unreceivedMessages, $index, 1);
  
          return $this;
      }
docs: @param int $index
  
  @throws Exception\OutOfRangeException
  
  @return $this