public static Func <Flight <Airport, Airline>, string> MapRow(DateTime day)
=> (Flight <Airport, Airline> a)
=> string.Join(',', new[] { $"{a.FlightNumber}_{day.ToString("yyyyMMdd")}", AirportDay.Create(a.To, day).Code, $"{a.From.Code}_FLIGHT" });
public static Func <Airport, string> MapRow(DateTime day)
=> (Airport a)
=> string.Join(',', new[] { a.Code, AirportDay.Create(a, day).Code });