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:                 |> List.toArray
              
              Error (String.Join(Environment.NewLine, errors) )
  
  
      [<EntryPoint>]
  
negative.code:                 (SurfaceArea.get assembly)
                  |> Json.serialize
                  |> Json.formatWith JsonFormattingOptions.Pretty
                  |> Ok
              | None, Some ( original,new_), None ->
                  getDiff original new_
                  |> Result.map (fun diff->
                      diff
                      |> Json.serialize
                      |> Json.formatWith JsonFormattingOptions.Pretty
                      ) 
              | None, None, Some (original,new_) ->
                  getDiff original new_
                  |> Result.map (fun diff->
                      let magnitude = Compare.packageChangeMagnitude diff
                      magnitude.ToString()
                      ) 
               | _, _,_ ->
                  Error(parser.PrintUsage())
          |> writeResult