/** Bubble $evt up the stack calling $target() on each listener */
 private function _bubble(Swift_Events_EventObject $evt, $target)
 {
     if (!$evt->bubbleCancelled() && ($listener = array_shift($this->_bubbleQueue))) {
         $listener->{$target}($evt);
         $this->_bubble($evt, $target);
     }
 }

 /**
  * Create a new CommandEvent for $source with $command.
  * @param Swift_Transport $source
  * @param string $command
  * @param array $successCodes
  */
 public function __construct(Swift_Transport $source, $command, $successCodes = array())
 {
     parent::__construct($source);
     $this->_command = $command;
     $this->_successCodes = $successCodes;
 }

 /**
  * Create a new ResponseEvent for $source and $response.
  *
  * @param Swift_Transport $source
  * @param string          $response
  * @param bool            $valid
  */
 public function __construct(Swift_Transport $source, $response, $valid = false)
 {
     parent::__construct($source);
     $this->_response = $response;
     $this->_valid = $valid;
 }

 /**
  * Create a new SendEvent for $source and $message.
  *
  * @param Swift_Transport    $source
  * @param Swift_Mime_Message $message
  */
 public function __construct(Swift_Transport $source, Swift_Mime_Message $message)
 {
     parent::__construct($source);
     $this->_message = $message;
     $this->_result = self::RESULT_PENDING;
 }

 /**
  * Create a new TransportExceptionEvent for $transport.
  * @param Swift_Transport $transport
  * @param Swift_TransportException $ex
  */
 public function __construct(Swift_Transport $transport, Swift_TransportException $ex)
 {
     parent::__construct($transport);
     $this->_exception = $ex;
 }