anchor.diff:  
   regroup_ast(ListVariable, GrouperVariable, LocalVarName, TreeWalker) ->
       {{ListAst, ListInfo}, TreeWalker1} = value_ast(ListVariable, false, true, TreeWalker),
  -    LocalVarAst = varify(LocalVarName),
  +    LocalVarAst = varname_ast(LocalVarName),
   
       {Id, TreeWalker2} = begin_scope(
                             {[{LocalVarName, LocalVarAst}],
  
positive.code:     {Scope, Values} =
          lists:foldl(
            fun ({Name, Value}, {VarAcc, ValueAcc}) ->
                    NameAst = merl:var(lists:concat(["_Var_", Name, VarScope])),
                    {[{Name, NameAst}|VarAcc],
                     [?Q("_@NameAst = _@Value")|ValueAcc]
                    }
  
negative.code: 
      NewScope = lists:map(
                   fun ({{identifier, _, LocalVarName}, _Value}) ->
                           {LocalVarName, varname_ast(LocalVarName)}
                   end,
                   ArgList),
  
  