private function registerFormMacros($app)
    {
        foreach ([FormBuilder::class, 'form'] as $alias) {
            if ($app->bound($alias)) {
                $app[$alias]->macro('captcha', function($name = null) use ($app) {
                    return $app[Contracts\NoCaptcha::class]->input($name);
                });
            }
        }
    }