anchor.diff:                      let blockString = blockToString block
   
                       out.WriteLine (sprintf "%d [label=\"%s\",shape=box]"  !count blockString)
  -                    blockToNumber.Add (block, !count)
  +                    blockToNumber.[block] <- !count
                       !count, true
   
               let nodeNumber, isNew = getBlockNumber block
  
positive.code:             let data = 
                  if not <| vertexToTokens.ContainsKey vertex 
                  then 
                      vertexToTokens.Add (vertex, [[]])
                  vertexToTokens.[vertex]
              
              this.OutEdges vertex
  
negative.code:                 then
                      let varName = tok |> tokToSourceString
  
                      //Is it error?
                      if not <| List.exists (fun t -> t = varName) !defVars
                      then
                          let tokData = parserSource.tokenData tok
                          //is it new error?
                          if not <| List.exists (fun t -> parserSource.tokenData t = tokData) !errorList     
                          then errorList := tok :: !errorList 
  
  