lib/AktiveMerchant/Billing/Gateway.php
public function addListener($eventName, $listener, $priority = 0)
    {
        $this->getDispatcher()->addListener($eventName, $listener, $priority);
    }
public function addListener($eventName, $listener, $priority = 0)
    {
        $this->getDispatcher()->addListener($eventName, $listener, $priority);
    }
public function addListener ( $ eventName , $ listener , $ priority = 0 ) { $ this -> getDispatcher ( ) -> addListener ( $ eventName , $ listener , $ priority ) ; }
Add a listener to gateway event.

@param string $eventName
@param string $listener
@param int $priority

@return void
Add a listener to gateway event .