anchor.diff:  [<NoComparison>]
   type private FastStageData =
       { Snapshot: ITextSnapshot
  -      OpenDeclarations: OpenDeclaration list  
  -      AllEntities: Map<string, Idents list> option
         Spans: CategorizedColumnSpan[]
         SymbolUses: SymbolUse[]
         SingleSymbolsProjects: CheckingProject list }
  
positive.code: [<NoComparison>]
  type private SlowStageData =
      { Snapshot: ITextSnapshot 
        UnusedSpans: Map<WordSpan, CategorizedColumnSpan> }
  
  [<NoComparison>]
  type private SlowStage =
      | NoData
      | Data of SlowStageData
  
  type SyntaxConstructClassifier
  
negative.code:     interface IDisposable with
          member __.Dispose() = 
              events |> Option.iter (fun e -> e.BuildEvents.remove_OnBuildProjConfigDone onBuildDoneHandler)
              fastStageCancellationToken.Value
              |> Option.iter (fun token -> 
                  token.Cancel()
                  token.Dispose())
  