anchor.diff:      | [<PrintLabels>] Min          of hours:string
       | [<PrintLabels>] Max          of hours:string
       | [<PrintLabels>] ArriveBefore of hour:string
  -    | DepCont      of string
  -    | ArrCont      of string
  -    | DepType      of string
  -    | ArrType      of string
  -    | Sort         of string
  +    | [<PrintLabels>] Arrival      of icao:string
  +    | DepCont of string
  +    | ArrCont of string
  +    | DepType of string
  +    | ArrType of string
  +    | Sort    of string
       with
           interface IArgParserTemplate with
               member s.Usage =
  
positive.code:                 | Min _          -> "specify the minimum time for routes"
                  | Max _          -> "specify the maximum time for routes"
                  | ArriveBefore _ -> "set the local time that routes must arrive by"
                  | DepCont _      -> "set the continent for the departure airport"
                  | ArrCont _      -> "set the continent for the arrival airport"
                  | DepType _      -> "set the type of airport for the departure"
  
negative.code:             | Min          (Time t)   -> Filter.MinTime t            |> Some
              | Max          (Time t)   -> Filter.MaxTime t            |> Some
              | ArriveBefore (Time t)   -> Filter.ArriveBefore t       |> Some
              | Arrival icao            -> Filter.ArrivalAirport icao  |> Some
              | DepCont c               -> Filter.DepartureContinent c |> Some
              | ArrCont c               -> Filter.ArrivalContinent c   |> Some
              | DepType (AirportType t) -> Filter.DepartureType t      |> Some
  