Natools

                 Parent => Parent,
                 Next => null,
                 Data => new Atom'(N.Data.all));
            when List_Node =>
               Result := new Node'(Kind => List_Node,
                 Parent => Parent,
                 Next => null,
                 Child => Dup_List (N.Child, N));
                 Child => null);
               Result.Child := Dup_List (N.Child, Result);
         end case;

         if N = Source.Last then
            New_Last := Result;
         end if;

         return Result;