anchor.diff:  
   type Processor<'TokenType,'br, 'range, 'node>  when 'br:equality and  'range:equality and 'node:null
       (
  -        tokenize: Appr<'br> -> ParserInputGraph<'TokenType>
  +        //tokenize: Appr<'br> -> ParserInputGraph<'TokenType>
  +        tokenize: Appr<'br> -> Test<ParserInputGraph<'TokenType>, array<Smbl<char * Position<'br>>>>
           , parse, translate, tokenToNumber: 'TokenType -> int, numToString: int -> string, tokenData: 'TokenType -> obj, tokenToTreeNode, lang, calculatePos:_->seq<'range>
           , getDocumentRange:'br -> 'range
           , printAst: Tree<'TokenType> -> string -> unit
  
positive.code:             lexingFinished.Trigger(new LexingFinishedArgs<'node>(tokensList, lang))
  
      let processLang graph addLError addPError =
          let tokenize g =
              try 
                  tokenize g
                  |> Some 
              with
              | LexerError(t,grToken) ->
                  (t, (grToken :?> GraphTokenValue<'br>).Edges |> Seq.nth 0 |> fun e -> e.BackRef |> getDocumentRange)
                  |> addLError
                  None
  
          
          let tokenizedGraph = tokenize graph 
          prepareToHighlighting tokenizedGraph tokenToTreeNode 
  
          tokenizedGraph 
          |> Option.map parse
          |> Option.iter
              (function 
                  | Yard.Generators.RNGLR.Parser.Success(tree, _, errors) ->
  
negative.code:         let lexerErrors = new ResizeArray<_>()
  
          let addError tok =
              let e tokName (tokenData: GraphTokenValue<'br>) = 
                  tokenData |> calculatePos
                  |> Seq.iter
                      ///TODO!!! Produce user friendly error message!
                      (fun br -> parserErrors.Add <| ((sprintf "%A" tokName), br))
              let name = tok |> (tokenToNumber >>  numToString)
              let tokenData = tokenData tok :?> GraphTokenValue<'br>
              e name tokenData
          
          
          processLang graph lexerErrors.Add addError
  