anchor.diff:          | _ -> failwith "Unexpected state in tree generation"
   
       member this.TokenToPos calculatePos (token : 'TokenType)= 
  -        let data : string * FSA<char*Position<'br>> = unbox <| tokenData token
  -        calculatePos <| snd data
  +        let data (*: FSA<char*Position<'br>>*) = unbox <| tokenData token
  +        calculatePos data
   
       member this.GetForestWithToken range = getForestWithToken range
   
  
positive.code:     member this.TranslateToTreeNode nextTree errors = (Seq.head <| translate nextTree errors)
      
      member this.Process (graph:Appr<_>) = 
          let parserErrors = new ResizeArray<_>()
          let lexerErrors = new ResizeArray<_>()
          let parserErrors = new ResizeArray<_>()
          let semanticErrors = new ResizeArray<_>()
  
          let addError tok isParse =
              let e tokName (tokenData: FSA<char*Position<'br>>) = 
                  tokenData |> calculatePos
                  |> Seq.iter
                      ///TODO!!! Produce user friendly error message!
                      (fun br -> if isParse 
  
negative.code:                         let semErrors = cfg.FindUndefVariable()
                          semErrors |> List.iter addSError
  
                  | Yard.Generators.ARNGLR.Parser.Error(_, tok, _) -> 
                      if tok <> Unchecked.defaultof<'TokenType>
                      then tok |> addPError 
              )
  
      let getNextTree index : TreeGenerationState<'node> = 
  