anchor.diff:                  then
                       let prefixesToAdd = new ResizeArray<Prefix<_>>()
   
  -                    prefixesToAdd.Add(newPrefix gssVertexesToPrefixes.[gssVertex] e)
  +                    prefixesToAdd.Add(extPrefix gssVertexesToPrefixes.[gssVertex] e)
                       addEdge e.Target isNew tailGssV edge true prefixesToAdd    //push case
   
           if not <| currentGraphV.processedGssVertices.Contains(gssVertex)
  
positive.code:                 levels.[u.Level] <- [!curNum]
              else
                  levels.[u.Level] <- !curNum :: levels.[u.Level]
              //print <| sprintf "%d [label=\"%d_%d\"]" !curNum u.Level u.State 
              let rec printPrefixes (prefixes:ResizeArray<Prefix<_>>) (prevStr : string) =
                  let mutable curStr = prevStr + "["
                  if ResizeArray.isEmpty(prefixes) then curStr + "]"
                  else
                      for prefix in prefixes do
                          if prefix <> null
                          then
                              curStr <- curStr + prefix.Head.Tag.ToString() + ":"
                              curStr <- printPrefixes prefix.Tail curStr
                      curStr
                          
              print <| sprintf "%d [label=\"%d_%d_%s\"]" !curNum u.Level u.State (printPrefixes gssVertexesToPrefixes.[u] "Prefixes:")
              incr curNum
  
negative.code:                     let tree = new Tree<_>(terminals.ToArray(), nodes.[res], parserSource.Rules, Some parserSource.LeftSide, Some parserSource.NumToString)
  //                    tree.AstToDot parserSource.NumToString parserSource.TokenToNumber parserSource.TokenData parserSource.LeftSide "../../../Tests/AbstractRNGLR/DOT/sppf.dot"
  //
                      let gssInitVertices = 
                         innerGraph.Edges |> Seq.collect (fun e -> e.Source.processedGssVertices)
  
                      drawDot parserSource.TokenToNumber terminals parserSource.LeftSide gssInitVertices parserSource.NumToString parserSource.ErrorIndex "../../../Tests/AbstractRNGLR/DOT/gss.dot"
  
                      Success <| tree
                  with
  