anchor.diff:      %% setup
       VarScope = lists:map(
                    fun({identifier, {R, C}, Iterator}) ->
  -                         {Iterator, varify(lists:concat([
  +                         {Iterator, varname_ast(lists:concat([
                                       Iterator,"/", Level, "_", R, ":", C]))}
                    end, IteratorList),
       {Iterators, IteratorVars} = lists:unzip(VarScope),
  
positive.code: 
  regroup_ast(ListVariable, GrouperVariable, LocalVarName, TreeWalker) ->
      {{ListAst, ListInfo}, TreeWalker1} = value_ast(ListVariable, false, true, TreeWalker),
      LocalVarAst = varify(LocalVarName),
  
      {Id, TreeWalker2} = begin_scope(
                            {[{LocalVarName, LocalVarAst}],
  
negative.code:     {Scope, Values} =
          lists:foldl(
            fun ({Name, Value}, {VarAcc, ValueAcc}) ->
                    NameAst = varname_ast(lists:concat(["_", Name, VarScope])),
                    {[{Name, NameAst}|VarAcc],
                     [?Q("_@NameAst = _@Value")|ValueAcc]
                    }
  