anchor.diff:      NCount = lists:foldl(fun(N, AccN) ->
                                    AccN + node_size(N)
                            end, 0, ChildNodes),
  -    {nil, 1 + NCount, ItemCount + length(KeyList), Interval, ChildNodes}.
  +    % hash the bucket now:
  +    Hash = run_inner_hf(ChildNodes, Config#mt_config.inner_hf),
  +    {Hash, 1 + NCount, ItemCount + length(KeyList), Interval, ChildNodes}.
   
   -spec build_childs([{I::intervals:continuous_interval(), Count::non_neg_integer(),
                        mt_bucket()}], mt_config(), Acc::[mt_node()]) -> [mt_node()].
  
positive.code: 
  %% @doc Hashes a leaf with the given (sorted!) bucket.
  -spec run_leaf_hf(mt_bucket(), intervals:interval(), LeafHf::leaf_hash_fun())
          -> mt_node_key().
  run_leaf_hf(Bucket, I, LeafHf) ->
      ?DBG_ASSERT(lists:ukeysort(1, Bucket) =:= Bucket),
      Hash = LeafHf(Bucket, I),
      Size = erlang:bit_size(Hash),
      <<SmallHash:Size/integer-unit:1>> = Hash,
      SmallHash.
  
  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  
  
negative.code:     KeepBucket = Config#mt_config.keep_bucket,
      Node = if Count > BucketSize ->
                    p_bulk_build({nil, 0, [], Interval}, Config, Bucket);
                true ->
                    % hash the bucket now:
                    {Bucket1, Hash} = run_leaf_hf(Bucket, Interval, Config#mt_config.leaf_hf),
                    {Hash, Count, ?IIF(KeepBucket, Bucket1, []), Interval}
             end,
      build_childs(T, Config, [Node | Acc]);
  build_childs([], _, Acc) ->
  