anchor.diff:          |> List.map 
               (
                   fun kvp ->
  -                    let text = 
  -                        match kvp.Value with
  -                        | RootNode -> "root"
  -                        | InnerNode(nodeInfo) -> nodeInfo.Label
  +                    let text = kvp.Value.Label
                       kvp.Key.ToString() + " [label=\"" + text + "\"]"
               )
           |> List.iter file.WriteLine
  
positive.code:         let finalNodeId, provider = NodeIdProviderFuncs.getId provider varRef
          let varName = varRef.NameIdentifier.Name
          let finalNodeInfo = { Label = "varRef(" + varName + ")"; AstElem = varRef }
          let graphInfo = DDGBuildFuncs.create(finalNodeId, InnerNode(finalNodeInfo))
          let varsSet = Set.ofList [varName]
          let cfgNode = getCorespondingCfgNode varRef |> fun w -> w.Value
          let initState = { 
  
negative.code: 
      type private DDGraphBuildInfo = {   
          Graph: AdjacencyGraph<int, Edge<int>>
          NodeIdInfoDict: Dictionary<int, NodeInfo>
          ConnectionNode: int }
  
      module private DDGBuildFuncs =
          // exception messages
  