/**
  * @return common_persistence_AdvKeyValuePersistence
  */
 public function getPersistence()
 {
     return common_persistence_AdvKeyValuePersistence::getPersistence($this->getOption(self::OPTION_PERSISTENCE));
 }
 private function getPersistence()
 {
     $persistence = common_persistence_AdvKeyValuePersistence::getPersistence('keyValueResult');
     // check that persistence is a correct Key VAlue persistence
     return $persistence;
 }