public function __construct($function, $options = null)
 {
     parent::__construct();
     $this->function = $function;
     if ($options != null) {
         if ($options instanceof Options) {
             $this->options = $options;
         } else {
             throw new \InvalidArgumentException('DefaultJQueryUIBehaviour::__construct expected argument 2 to be an an Options object');
         }
     } else {
         $this->options = new Options();
     }
 }