public static function instance()
 {
     if (self::$_instance == null) {
         self::$_instance = new self();
         return self::$_instance;
     } else {
         return self::$_instance;
     }
 }
 public static function returnInstance()
 {
     switch ($_SESSION['lang']) {
         case 'en':
             Tools::import('Lang.EnLanguage');
             return Lang_EnLanguage::instance();
             break;
         case 'lv':
             Tools::import('Lang.LvLanguage');
             return Lang_LvLanguage::instance();
             break;
         case 'cn':
             Tools::import('Lang.CnLanguage');
             return Lang_CnLanguage::instance();
             break;
         default:
             Tools::import('Lang.CnLanguage');
             return Lang_CnLanguage::instance();
             break;
     }
 }