/**
  * Returns a unique instance (Singleton) of the object. Use this method instead of the private/protected class constructor.
  *
  * @param   void
  * @return  Tx_PtExtbase_State_Session_Storage_FeUserSessionAdapter      unique instance of the object (Singleton)
  */
 public static function getInstance()
 {
     if (self::$uniqueInstance === null) {
         $className = __CLASS__;
         self::$uniqueInstance = new $className();
     }
     return self::$uniqueInstance;
 }