anchor.diff:  
           let docKey = "MyCountingDoc/" + Guid.NewGuid().ToString()
   
  -        seq {
  -            yield (docKey, new MyCountingDoc(), null)
  -        }
  -        |> BatchOperations.writeBatch documentStore 
  -        |> Async.Ignore
  -        |> Async.RunSynchronously
  +        let result = 
  +            seq {
  +                yield (docKey, new MyCountingDoc(), null, (fun _ -> async { () }))
  +            }
  +            |> BatchOperations.writeBatch documentStore 
  +            |> Async.RunSynchronously
  +
  +        match result with
  +        | Some _ -> (true |> should equal true)
  +        | None -> (false |> should equal true)
   
       [<Fact>]
       let ``Pump many events at Raven`` () : unit =
  
positive.code:         cmd
          
      let writeBatch (documentStore : Raven.Client.IDocumentStore) (docs:seq<BatchWrite>) = async {
          let! batchResult = 
              docs
              |> Seq.map buildPutCommand
              |> Seq.cast<ICommandData>
              |> Array.ofSeq
              |> documentStore.AsyncDatabaseCommands.BatchAsync
              |> Async.AwaitTask
  
          return (batchResult, docs)
      }
  
      
  
negative.code: 
          let myEvents = (streams, streamValues) |> Seq.unfold generateStream
  
          let rec runUntilSuccess task = async {
              try
                  return! task()
              with 
              | e -> return! runUntilSuccess task
          }
              
          seq {
              yield async {
                  for (key,value) in myEvents do
  