anchor.diff:                  | _ ->
                       let astNode = cfe.SourceElement
                       match astNode with
  -                    | AppropNameAssignExpr(assignExpr) -> 
  +                    | TrackedVarAssignExpr(assignExpr) -> 
                           let assingnType, operands = 
                               if assignExpr.AssignmentType = AssignmentType.EQ
                               then 
  
positive.code:                         let entries = cfe.Entries |> List.ofSeq
                          entries, state', varsSet
                      // not implemented (but must precede IReferenceExpression case)
                      | :? IInvocationExpression -> 
                          cfe.Entries |> List.ofSeq, state, varsSet
                      | :? IReferenceExpression as refExpr 
                          when Set.contains cfe.Id state.RefExprsToVisit 
  
negative.code:             else cfgNodes |> List.ofSeq |> List.head
  
          let rec build (cfe: IControlFlowElement) (varsSet: Set<string>) (state: BuildState) =
              let (|TrackedVarAssignExpr|_|) (node: ITreeNode) =
                  match node with
                  | :? IAssignmentExpression as assignExpr 
                      when 
  