function uncancel($slug, Request $request, Application $app)
 {
     if (!$this->build($slug, $request, $app)) {
         $app->abort(404, "Event does not exist.");
     }
     //TODO It's inefective to get them all when really we just want the latest one!
     $ehrb = new EventHistoryRepositoryBuilder();
     $ehrb->setEvent($this->parameters['event']);
     $ehrb->setOrderByCreatedAt(true);
     $eventHistories = $ehrb->fetchAll();
     $eventHistory = $eventHistories[0];
     return $app->redirect("/event/" . $this->parameters['event']->getSlugForURL() . '/rollback/' . $eventHistory->getCreatedAtTimeStamp());
 }