static function __static()
 {
     self::$UNKNOWN = new self(0, 'UNKNOWN', xp::null(), xp::null());
     self::$JSON = new self(1, 'JSON', new RestJsonSerializer(), new RestJsonDeserializer());
     self::$XML = new self(2, 'XML', new RestXmlSerializer(), new RestXmlDeserializer());
     self::$FORM = new self(3, 'FORM', xp::null(), new RestFormDeserializer());
 }