/**
  * resturns a single instance of this class
  *
  * @return oxUtils
  */
 public static function getInstance()
 {
     // disable caching for test modules
     if (defined('OXID_PHP_UNIT')) {
         self::$_instance = modInstances::getMod(__CLASS__);
     }
     if (!self::$_instance instanceof oxUtils) {
         self::$_instance = oxNew('oxUtils');
         if (defined('OXID_PHP_UNIT')) {
             modInstances::addMod(__CLASS__, self::$_instance);
         }
     }
     return self::$_instance;
 }