anchor.diff:      let buffer = textDocument.TextBuffer
       let tagsChanged = Event<_,_> ()
       let mutable scopedSnapSpans : ScopedSpan [] = [||]
  +    let mutable oldAST = None : ParsedInput option
  +
   
       let tagTrigger () =
           tagsChanged.Trigger (self, SnapshotSpanEventArgs buffer.CurrentSnapshot.FullSpan)
  
positive.code:             let line = snapshot.GetLineFromLineNumber(lineNumber)
              let lineStart = line.Start.Position
              spansToElide.Add(Span.FromBounds(lineStart, lineStart + indentationColumn))
                  
          elisionBuffer.ElideSpans(NormalizedSpanCollection(spansToElide)) |> ignore
  
          match suffixOpt with
  
negative.code:             let currentWidth = view.VisualElement.Width
              if isNormal newWidth && isNormal currentWidth && newWidth <= currentWidth then ()
              else
                  view.VisualElement.Width <- view.MaxTextRightCoordinate))
          |> ignore)
  
  type OutliningTagger
      (textDocument: ITextDocument,
  