public function getNotes(Request $request, $id)
 {
     $qcm = Qcm::with('subject', 'participations', 'participations.answer', 'participations.user')->findOrFail($id);
     $participations = $qcm->participations;
     $results = [];
     foreach ($participations as $participation) {
         if (!isset($results[$participation->user_id])) {
             $results[$participation->user_id] = new class($participation->user)
             {
                 public $user;
                 public $points;
                 public function __construct($user)
                 {
                     $this->user = $user;
                     $this->points = 0;
                 }
             };
         }
         $answer = $participation->answer;
         $results[$participation->user_id]->points += $answer->isValid;
     }
     return view('qcm.teacher.notes', compact('qcm', 'results'));
 }