protected function supports($attribute, $subject)
    {
        // if the attribute isn't one we support, return false
        if (!in_array($attribute, array(self::MENU, self::PERMISO))) {
            return false;
        }

        if ($attribute == self::MENU && !is_null($subject) && !$subject instanceof Menu) {
            return false;
        }

        return true;
    }