public TeacherViewModel(Teacher teacher, ExamDbContext db)
        {
            this.db        = db;
            CurrentTeacher = teacher;

            CurrentChatVM       = new ShowStudentsViewModel(CurrentTeacher, db, ShowChat, "Открыть чат");
            CurrentStatisticsVM = new ShowStudentsViewModel(CurrentTeacher, db, ShowStatistics, "Статистика");
        }
 private void ShowChatStudents()
 {
     CurrentChatVM = new ShowStudentsViewModel(CurrentTeacher, db, ShowChat, "Открыть чат");
 }