anchor.diff:        update(lists:concat(["key", N]), lists:concat(["different", N]), Tree)
       end, lists:foldl(fun(N, Tree) ->
           update(lists:concat(["key", N]), lists:concat(["value", N]), Tree)
  -      end, open("/Users/cliff/data/dmerkle1", 256), lists:seq(1,500)), lists:seq(1, 500)),
  +      end, open(data_file(1), 256), lists:seq(1,500)), lists:seq(1, 500)),
     Diff = key_diff(TreeA, TreeB),
     500 = length(Diff),
     500 = length(leaves(TreeB)).
  
positive.code: data_file() ->
      filename:join(priv_dir(), "dmerkle").
     
  
negative.code:     end, open(data_file(), 256), lists:seq(1,500)),
    TreeB = lists:foldl(fun(N, Tree) ->
        update(lists:concat(["key", N]), lists:concat(["value", N]), Tree)
      end, open(data_file(1), 256), lists:reverse(lists:seq(1,250))),
    NewTree = swap_tree(TreeA, TreeB),
    SameTree = open(data_file(), 256),
    error_logger:info_msg("trees: ~p ~p~n", [NewTree, SameTree]),
  