private List <Appointment> GetFreeAppointmentsUntilTaken(TimeIterator timeIterator, Appointment takenAp, Doctor doctor)
        {
            List <Appointment> freeAppointments = new List <Appointment>();

            while (!takenAp.TimeInterval.IsOverlappingWith(timeIterator.GetCurrentTimeFrame()))
            {
                freeAppointments.Add(GetFreeAppointment(timeIterator, doctor));
                timeIterator.Next();
            }

            return(freeAppointments);
        }
 private Appointment GetFreeAppointment(TimeIterator timeIt, Doctor doctor)
 {
     return(new Appointment(doctor, null, null, AppointmentType.checkup, timeIt.GetCurrentTimeFrame()));
 }