static function get_instance()
 {
     if (!isset(self::$_instance)) {
         $klass = get_class();
         self::$_instance = new $klass();
     }
     return self::$_instance;
 }
 function render_order_verification()
 {
     $controller = C_NextGen_Pro_Order_Verification::get_instance();
     return $controller->render($_REQUEST['order']);
 }