public function get($format)
    {
        switch ($format) {
            case 'json':
                return $this->toJson();
                break;
            case 'serialize':
                return $this->serialize();
                break;
            case 'array':
                return $this->toArray();
                break;
            case 'xml':
                return $this->toXml();
                break;
            default:
                return $this;
        }
    }