anchor.diff:  
               let textSnapshot = openingPoint.Snapshot
   
  -            session <-
  +            let newSession =
                   match textSnapshot.GetOpenDocumentInCurrentContextWithChanges() with
                   | null -> null
                   | document ->
  
positive.code:             // TODO: Implement this for F#
              true 
  
  [<Shared>]
  [<ExportLanguageService(typeof<IEditorBraceCompletionSessionFactory>, FSharpConstants.FSharpLanguageName)>]
  type internal FSharpEditorBraceCompletionSessionFactory 
          [<ImportingConstructor>] (_smartIndetationService: ISmartIndentationService, _undoManager: ITextBufferUndoManagerProvider) =
      inherit ForegroundThreadAffinitizedObject ()
  
      member __.IsSupportedOpeningBrace openingBrace =
  
negative.code: 
                      snapshot <-
                          use edit = subjectBuffer.CreateEdit()
  
                          edit.Insert(closingSnapshotPoint.Position, closingBrace.ToString()) |> ignore
                      
                          if edit.HasFailedChanges then
                              Debug.Fail("Unable to insert closing brace")
  