public function register()
 {
     //Classroom
     Classroom::created(function ($classroom) {
         UserLog::create(['operation' => 'create', 'user_id' => user() ? user()->id : NULL, 'reference_key' => 'classrooms', 'reference_id' => $classroom->id]);
     });
     Classroom::updated(function ($classroom) {
         UserLog::create(['operation' => 'update', 'user_id' => user() ? user()->id : NULL, 'reference_key' => 'classrooms', 'reference_id' => $classroom->id]);
     });
     Classroom::deleted(function ($classroom) {
         UserLog::create(['operation' => 'delete', 'user_id' => user() ? user()->id : NULL, 'reference_key' => 'classrooms', 'reference_id' => $classroom->id]);
     });
     //ClassroomInterval
     ClassroomInterval::created(function ($classroominterval) {
         UserLog::create(['operation' => 'create', 'user_id' => user() ? user()->id : NULL, 'reference_key' => 'classroom_intervals', 'reference_id' => $classroominterval->id]);
     });
     ClassroomInterval::updated(function ($classroominterval) {
         UserLog::create(['operation' => 'update', 'user_id' => user() ? user()->id : NULL, 'reference_key' => 'classroom_intervals', 'reference_id' => $classroominterval->id]);
     });
     ClassroomInterval::deleted(function ($classroominterval) {
         UserLog::create(['operation' => 'delete', 'user_id' => user() ? user()->id : NULL, 'reference_key' => 'classroom_intervals', 'reference_id' => $classroominterval->id]);
     });
     //ClassroomSessionExcuse
     ClassroomSessionExcuse::created(function ($classroomsessionexcuses) {
         UserLog::create(['operation' => 'create', 'user_id' => user() ? user()->id : NULL, 'reference_key' => 'classroom_session_excuses', 'reference_id' => $classroomsessionexcuses->id]);
     });
     ClassroomSessionExcuse::updated(function ($classroomsessionexcuses) {
         UserLog::create(['operation' => 'update', 'user_id' => user() ? user()->id : NULL, 'reference_key' => 'classroom_session_excuses', 'reference_id' => $classroomsessionexcuses->id]);
     });
     ClassroomSessionExcuse::deleted(function ($classroomsessionexcuses) {
         UserLog::create(['operation' => 'delete', 'user_id' => user() ? user()->id : NULL, 'reference_key' => 'classroom_session_excuses', 'reference_id' => $classroomsessionexcuses->id]);
     });
     //ClassroomSession
     ClassroomSession::created(function ($classroomsession) {
         UserLog::create(['operation' => 'create', 'user_id' => user() ? user()->id : NULL, 'reference_key' => 'classroom_sessions', 'reference_id' => $classroomsession->id]);
     });
     ClassroomSession::updated(function ($classroomsession) {
         UserLog::create(['operation' => 'update', 'user_id' => user() ? user()->id : NULL, 'reference_key' => 'classroom_sessions', 'reference_id' => $classroomsession->id]);
     });
     ClassroomSession::deleted(function ($classroomsession) {
         UserLog::create(['operation' => 'delete', 'user_id' => user() ? user()->id : NULL, 'reference_key' => 'classroom_sessions', 'reference_id' => $classroomsession->id]);
     });
 }