/**
  * Returns an instance of the cacheManager singleton.
  *
  * @return  tx_languagevisibility_cacheManager
  */
 public static function getInstance()
 {
     if (!self::$instance instanceof tx_languagevisibility_cacheManager) {
         self::$instance = new tx_languagevisibility_cacheManager();
     }
     return self::$instance;
 }