public function setFlag($wikiId, $flag, $corpWikiId, $langCode)
 {
     wfProfileIn(__METHOD__);
     /* @var $visualization CityVisualization */
     $visualization = new CityVisualization();
     $result = $visualization->setFlag($wikiId, $langCode, $flag);
     if ($result === true) {
         //purge cache
         //wiki cache
         $visualization->getList($corpWikiId, $langCode, true);
         $memcKey = $visualization->getWikiDataCacheKey($visualization->getTargetWikiId($langCode), $wikiId, $langCode);
         $this->wg->Memc->set($memcKey, null);
         //visualization list cache
         $visualization->purgeVisualizationWikisListCache($corpWikiId, $langCode);
         wfProfileOut(__METHOD__);
         return true;
     }
     wfProfileOut(__METHOD__);
     return false;
 }