anchor.diff:  
           let all = results.GetAllResults()
           if List.isEmpty all || results.IsUsageRequested then
  -            Console.WriteLine(parser.PrintUsage())
  -            1
  +            Error(parser.PrintUsage())
           else
               let maybeFile = results.TryGetResult(<@ Surface_of @>)
               let maybeDiff = results.TryGetResult(<@ Diff @>)
  
positive.code: type Result<'T,'TError> = 
           | Ok of 'T 
           | Error of 'TError
  
  module Program=
      let surfaceAreaCli file=
  
negative.code:                 |> List.toArray
              
              Error (String.Join(Environment.NewLine, errors) )
      let writeResult (res:Result<string,string>)=
          match res with
          | Ok msg-> Console.WriteLine msg ; 0
          | Error msg->Console.Error.WriteLine msg ; 1
  
  
      [<EntryPoint>]
  