protected function to()
    {
        if (static::$to === 1) {
            $method = 'renderAsArray';
        } elseif (static::$to === 2) {
            $method = 'renderAsJson';
        } elseif (static::$to === 3) {
            $method = 'renderAsHtml';
        } elseif (static::$to === 4) {
            $method = 'renderAsDropdown';
        } else {
            return $this->source;
        }

        $nest = new NestableService();
        $nest->save(static::$parameters);
        $nestable = $nest->make($this->source);

        static::$nested = false;

        return call_user_func([$nestable, $method]);
    }