/// <summary>
 /// Invoke HomeworksListChanging, HomewokIsReplaced and HomeworksListChanged events
 /// </summary>
 /// <param name="oldH">Old homework</param>
 /// <param name="newH">New homework</param>
 internal static void Call_HomewokIsReplaced(Homework oldH, Homework newH)
 {
     HomeworksListChanging?.Invoke(Global.userData.homeworks);
     HomewokIsReplaced?.Invoke(oldH, newH);
     HomeworksListChanged?.Invoke(Global.userData.homeworks);
 }
 /// <summary>
 /// Invoke HomeworksListChanging, HomeworkDeleted and HomeworksListChanged events
 /// </summary>
 /// <param name="homework">Deleted homework</param>
 internal static void Call_HomeworkDeleted(Homework homework)
 {
     HomeworksListChanging?.Invoke(Global.userData.homeworks);
     HomeworkDeleted?.Invoke(homework);
     HomeworksListChanged?.Invoke(Global.userData.homeworks);
 }