public int RemoveTutoringTime(DateTime date, string time, int teacherId)
        {
            TutoringTime tt = new TutoringTime();
            tt.Date = date;
            tt.Time = time;
            tt.Teacher = new Person(teacherId);

            ttDb = new TutoringTimeDb();

            return ttDb.RemoveTutoringTime(tt);
        }
        public int RemoveTutoringTime(int teacherId, DateTime date, string time)
        {
            TutoringTimeDb ttDb = new TutoringTimeDb();

            return ttDb.RemoveTutoringTime(teacherId, date, time);
        }