anchor.diff:          member __.BeginWrite(path : string) = async {
               let path = normalize path
               initDir <| Path.GetDirectoryName path
  -            return retry ioConcurrencyPolicy (fun () -> new FileStream(path, FileMode.Create, FileAccess.Write, FileShare.None) :> Stream)
  +            return retry fileAccessRetryPolicy (fun () -> new FileStream(path, FileMode.Create, FileAccess.Write, FileShare.None) :> Stream)
           }
   
           member __.BeginRead(path : string) = async {
  -            try return! retryAsync ioConcurrencyPolicy <| async { return new FileStream(normalize path, FileMode.Open, FileAccess.Read, FileShare.Read) :> Stream }
  +            try return! retryAsync fileAccessRetryPolicy <| async { return new FileStream(normalize path, FileMode.Open, FileAccess.Read, FileShare.Read) :> Stream }
               with :? DirectoryNotFoundException -> return raise <| new FileNotFoundException(path)
           }
   
           member self.CopyOfStream(source : Stream, target : string) = async {
               let target = normalize target
               initDir <| Path.GetDirectoryName target
  -            use! fs = retryAsync ioConcurrencyPolicy <| async { return new FileStream(target, FileMode.Create, FileAccess.Write, FileShare.None) }
  +            use! fs = retryAsync fileAccessRetryPolicy <| async { return new FileStream(target, FileMode.Create, FileAccess.Write, FileShare.None) }
               do! source.CopyToAsync fs
           }
   
  
positive.code:         }
  
          member __.DeleteDirectory(container : string, recursiveDelete : bool) = async {
              return 
                  try Directory.Delete(normalize container, recursiveDelete)
                  with :? DirectoryNotFoundException -> ()
          }
  
          member __.EnumerateDirectories(directory) = async {
  
negative.code:         }
  
          member __.DeleteFile(file : string) = async {
              try return! retryAsync fileDeleteRetryPolicy (async { return File.Delete(normalize file) })
              with :? DirectoryNotFoundException -> return ()
          }
  
  