anchor.diff:      /// Stack of contexts
       let setR = new System.Collections.Generic.Stack<ContextFSA<_>>(startContexts)  
                    
  -//    /// Checks for existing of context in SetU. If not adds it to SetU.
  -//    let containsContext (inputIndex: int<positionInInput>) (state : int<positionInGrammar>) (gssVertex : YC.GLL.GSS.GSSVertex) =        
  -//        let cond, current = gssVertex.U.TryGetValue state
  -//        if cond
  -//        then
  -//            true            
  -//        else
  -//            gssVertex.U.Add(state, inputIndex)
  -//            false
  -
       /// Adds new context to stack (setR)
       let pushContext (inputVertex : int<positionInInput>) (state : int<positionInGrammar>) vertex len =
           setR.Push(new ContextFSA<_>(inputVertex, state, vertex, len))
  
positive.code:         if outEdges <> null && outEdges.Length <> 0
          then
              let vertexKey = packVertexFSA curVertex.PositionInInput curVertex.PositionInGrammar
  
              //let cond, value = setP.TryGetValue vertexKey
              let value = curVertex.P.Add (curIndex, curLen)
  //            if cond
  //            then
  //                value.Add (curIndex, curLen)
  //            else
  //                let newList = new ResizableUsualOne<_>((curIndex, curLen))
  //                setP.Add(vertexKey, newList)
  
              for e in outEdges do
                  addContext curIndex e.Tag.StateToContinue e.Target (curLen + e.Tag.LengthOfProcessedString)
  
  
negative.code:              r.[input.Edges.[i].Start].Add i
          r
  
      let gss = new GSS()
  
      /// State of FSA.
  