anchor.diff:          | [| p |] -> { wsArgs with ProjectFile = p }
           | [| |] -> argError "Cannot find project file, specify argument --project"
           | _ -> argError "Multiple project files in folder, specify argument --project"
  -    | _ -> wsArgs+    | _ -> wsArgs
  
positive.code:         Some input.[start.Length ..]
      else None 
  
  let (|Cmd|_|) (cmd: Commands.ICommand) argv =
      match cmd.Parse argv with
      | Commands.NotRecognized -> None
  
negative.code: 
  let RecognizeWebSharperArg a wsArgs =
      match a with
      | Flag "--jsmap" v -> Some { wsArgs with SourceMap = v }
      //| "--dts" -> Some { wsArgs with TypeScript = true } 
      | "--wig" -> Some { wsArgs with ProjectType = Some WIG }
      | "--bundle" -> Some { wsArgs with ProjectType =  Some Bundle }
      | "--bundleonly" -> Some { wsArgs with ProjectType = Some BundleOnly }
      | "--html" -> Some { wsArgs with ProjectType = Some Html }
      | "--site" -> Some { wsArgs with ProjectType = Some Website }
      | Flag "--wswarnonly" v -> Some { wsArgs with WarnOnly = v }
      | Flag "--dce" v -> Some { wsArgs with DeadCodeElimination = v }
      | StartsWith "--ws:" wsProjectType ->
          Some { wsArgs with ProjectType = ProjectType.Parse(wsProjectType) }
      | Flag "--dlres" v -> Some { wsArgs with DownloadResources = v }
      | Flag "--printjs" v -> Some { wsArgs with PrintJS = v }
      | StartsWith "--wsoutput:" o ->
          Some { wsArgs with OutputDir = Some o }
      | StartsWith "--project:" p ->
          Some { wsArgs with ProjectFile = Path.Combine(Directory.GetCurrentDirectory(), p) }
      | Flag "--closures" v ->
          Some { wsArgs with AnalyzeClosures = Some v }
      | StartsWith "--closures:" c ->
          match c.ToLower() with
          | "movetotop" ->
              Some { wsArgs with AnalyzeClosures = Some true }
          | _ ->
              printfn "--closures:%s argument unrecognized, must be one of: true, false, movetotop" c
              Some wsArgs
      | _ -> 
          None
  