public function sub($id, $obj, $cb)
    {
        if (!isset($this->events[$id])) {
            return false;
        }
        return $this->events[$id]->sub($obj, $cb);
    }
public function sub($id, $obj, $cb)
    {
        if (!isset($this->events[$id])) {
            return false;
        }
        return $this->events[$id]->sub($obj, $cb);
    }
public function sub ( $ id , $ obj , $ cb ) { if ( ! isset ( $ this -> events [ $ id ] ) ) { return false ; } return $ this -> events [ $ id ] -> sub ( $ obj , $ cb ) ; }
Subcribe to event
@param  string $id Event ID
@param  object $obj Subscriber
@param  callable $cb Callback
@return boolean       Success
Subcribe to event