public function after($callback)
    {
        $container  = Container::getInstance();

        $this->on('after', function ($request, $response) use (&$container, &$callback) {
            try {
                $container->call($callback, func_get_args());
            } catch (\Exception $e) {
                $this->emit('error', [$request, $response, $e->getMessage()]);
            }
        });
    }