/**
  * @param $start \DateTime
  * @param $end \DateTime
  * @return string
  */
 public function analyzeAction(\DateTime $start, \DateTime $end)
 {
     $sessions = $this->sessionRepository->findByStartAndEnd($start, $end);
     $result = [];
     foreach ($sessions as $session) {
         $result[] = ['uid' => $session['uid'], 'title' => $session['title'], 'data' => $this->getTopicMap($session['uid'])];
     }
     $this->view->assign('value', $result);
 }