public function isSubscribed(AnEventSubscriberInterface $subscriber)
    {
        $handle = $subscriber->getHandle();
        return isset($this->_subscribers[$handle]);
    }
public function isSubscribed(AnEventSubscriberInterface $subscriber)
    {
        $handle = $subscriber->getHandle();
        return isset($this->_subscribers[$handle]);
    }
public function isSubscribed ( AnEventSubscriberInterface $ subscriber ) { $ handle = $ subscriber -> getHandle ( ) ; return isset ( $ this -> _subscribers [ $ handle ] ) ; }
Check if the handler is connected to a dispatcher

@param  object	The event dispatcher
@return boolean	TRUE if the handler is already connected to the dispatcher. FALSE otherwise.
Check if the handler is connected to a dispatcher