private async void BtnUpdate_OnClick(object sender, RoutedEventArgs e)
        {
            if (!isCreate)
            {
                var flight = ReadTextBoxesData();
                if (flight != null && _selectedFlight != null)
                {
                    try
                    {
                        await Service.Update(flight, _selectedFlight.Id);
                    }
                    catch
                    {
                        Info.Text = "Server error!";
                    }

                    var itemIndex = Flights.ToList().FindIndex(x => x.Id == _selectedFlight.Id);
                    var item      = Flights.ToList().ElementAt(itemIndex);
                    Flights.RemoveAt(itemIndex);
                    item    = flight;
                    item.Id = _selectedFlight.Id;
                    Flights.Insert(itemIndex, item);
                    TbNumber.Text  = "Number : " + item.Number;
                    TbDep.Text     = "Point of departure :" + item.PointOfDeparture;
                    TbDepTime.Text = "Departure time :" + item.DepartureTime;
                    TbDest.Text    = "Destination :" + item.Destination;
                    TbArrTime.Text = "Arrival time :" + item.ArrivelTime;
                    TbTicket.Text  = "Tickets : " + TicketsId(item);
                }
            }
        }
        private void DeleteFlights()
        {
            int i = 0;

            while (i < Flights.Count)
            {
                if (!Flights[i].isActual)
                {
                    Flights.RemoveAt(i);
                }
                else
                {
                    break;
                }
            }
        }