public void Create(TherapistId therapistId)
        {
            if (therapistId == TherapistId.Empty)
            {
                throw new ArgumentException("therapist identifier is invalid", nameof(therapistId));
            }

            ApplyChange(new TherapistCreatedEvent(therapistId));
        }
 public TherapistEvent(TherapistId therapistId)
 {
     TherapistId = therapistId;
 }
 public TherapistCreatedEvent(TherapistId therapistId)
     : base(therapistId)
 {
 }