public Appointment(CalendarId calendarId,
                    AppointmentTerm appointmentTerm,
                    string patientId)
 {
     Id          = new AppoitmentId(Guid.NewGuid());
     _calendarId = calendarId;
     _term       = appointmentTerm;
     _patientId  = patientId;
     AddDomainEvent(new AppointmentCreatedDomainEvent(Id));
 }
 internal static Appointment CreateNewAppoitment(
     CalendarId calendarId,
     AppointmentTerm appointmentTerm,
     string patientId)
 {
     return(new Appointment(
                calendarId,
                appointmentTerm,
                patientId
                ));
 }