public function save_dates(cm_info $cm, array $dates)
 {
     parent::save_dates($cm, $dates);
     // Fetch module instance from $mods array.
     $quiz = $this->mods[$cm->instance];
     $quiz->instance = $cm->instance;
     $quiz->coursemodule = $cm->id;
     // Updating date values.
     foreach ($dates as $datetype => $datevalue) {
         $quiz->{$datetype} = $datevalue;
     }
     // Calling the update event method to change the calender evenrs accordingly.
     quiz_update_events($quiz);
 }