anchor.diff:  [<AutoOpen>]
   module PathHelpers =
   
  +    let tryDeleteDir d =
  +        if Directory.Exists d then
  +            try 
  +                Directory.Delete(d, true)
  +                true
  +            with e -> 
  +                traceError (sprintf "could not delete directory %A" d)
  +                false
  +        else
  +            true
  +
       let deleteDir d =
           if Directory.Exists d then
               try Directory.Delete(d, true)
  
positive.code:         else
              false
  
      let latestModificationDate (folder : string) =
          let file = DirectoryInfo(folder).GetFileSystemInfos("*", SearchOption.AllDirectories) |> Seq.maxBy (fun fi -> fi.LastWriteTime)
          file.LastWriteTime
  
      let installSources () =
          let sourceLines =
              if File.Exists sourcesFileName then 
  
negative.code:             with e -> traceError (sprintf "could not delete %A" f)
  
  module AdditionalSources =
  
      // register the logger
      Logging.event.Publish.Subscribe (fun a -> 
          match a.Level with
              | TraceLevel.Error -> traceError a.Text
  