anchor.diff:  let main args =
       match readArguments args with
       | Some results ->
  -        let autoUpdateEnabled = results.GetResult(<@ AutoUpdate @>, defaultValue = true)
  +        let autoUpdateEnabled =
  +            tryGetArgValue (<@ AutoUpdate @>) results
  +            |> Option.defaultArg true
  +
           if autoUpdateEnabled then
               checkAndupdateAirportData ()
   
  -        results.GetAllResults()
  -        |> processAirports
  +        processAirports results
       | None -> ()
   
       0
positive.code:                 | AutoUpdate _   -> "set whether or not airport data will be automatically updated"
                  | MaxRoutes _    -> "set the maximum number of routes to display"
  
  let (|Time|_|) v =
      match TimeSpan.TryParse v with
      | (true, x) -> Some x
  
negative.code:         AppDomain.CurrentDomain.BaseDirectory
          "airports.csv"
  
  let processAirports (args : ParseResults<_>) =
      let filters =
          args.GetAllResults()
          |> List.choose (function
              | Min          (Time t)   -> Filter.MinTime t            |> Some
              | Max          (Time t)   -> Filter.MaxTime t            |> Some
  