S-1: New Appointment
1. The Receptionist asks the Patient for possible appointment times.
2. The Receptionist matches the Patient's desired appointment times with available dates and times and schedules the new appointment.
S-2: Cancel Appointment
1. The Receptionist asks the Patient for the old appointment time
2. The Receptionist finds the current appointment in the appointment file and cancel it.
S-3: Change Appointment
1. The Receptionist performs the S-2: cancel appointment subflow.
2. The Receptionist performs the S-1: new appointment subflow.