anchor.diff:  
   module TransactionLog = 
       //open ProtoBuf
  -    open MsgPack
       open MsgPack.Serialization
  -    open System.Text
       
       type Operation = 
           | Create = 1
  
positive.code:         try 
              sw.SearcherManager.Close()
              sw.IndexWriter.Close()
          with e as AlreadyClosedException -> ()
      
      /// Adds a document to this index.
      let addDocument (document : Document) (sw : T) = sw.TrackingIndexWriter.AddDocument(document) |> ignore
  
negative.code:         /// A hook for extending classes to execute operations after pending 
          /// added and deleted documents have been flushed to the Directory but 
          /// before the change is committed (new segments_N file written).
          override __.doAfterFlush() = 
              /// State can be null when the index writer is opened for the
              /// very first time
              if not (isNull state) then state.IncrementFlushCount() |> ignore
  