public static void SaveTransaction(TransactionHeaderViewModel ticket, bool recalculate)
        {
            if (UserService.GetLoggedInUser() == null)
            {
                throw new ArgumentException();
            }

            if (ConfigurationService.GetConfiguration() == null)
            {
                throw new InvalidOperationException("no valid configuration");
            }

            ticket.ReservationNumber = GetReservationNumber(UserService.Username);
            //ticket.OperatorId = Guid.NewGuid().ToString();
            ticket.SetLineNumbers();
            ticket.SetPaidAmount();
            ticket.SaveTicket();
        }
        public static void RecalculateTicket(TransactionHeaderViewModel model)
        {

        }