anchor.diff:          -> NewNode::mt_node().
   insert_to_node(Key, _CheckKey, {_H, Count, LeafCount = 1, Bucket, Interval, []} = N, Config)
     when Count >= 0 andalso Count < Config#mt_config.bucket_size ->
  -    case lists:member(Key, Bucket) of
  +    case lists:keymember(element(1, Key), 1, Bucket) of
           false -> {nil, Count + 1, LeafCount, [Key | Bucket], Interval, []};
           _     -> N
       end;
  
positive.code: gen_hash_node({_OldHash, Count, _LCnt, Bucket, Interval, [] = Childs},
                _InnerHf, LeafHf, true, CleanBuckets) ->
      % leaf node, no bucket contents, keep_bucket true
      Bucket1 = lists:ukeysort(1, Bucket),
      Hash = run_leaf_hf(Bucket1, Interval, LeafHf),
      {Hash, Count, 1, ?IIF(CleanBuckets, [], Bucket1), Interval, Childs}.
  
  
negative.code: -spec run_leaf_hf(mt_bucket(), intervals:interval(), LeafHf::hash_fun())
          -> mt_node_key().
  run_leaf_hf(Bucket, I, LeafHf) ->
      ?DBG_ASSERT(lists:ukeysort(1, Bucket) =:= Bucket),
      BinBucket = case Bucket of
                      [_|_] -> term_to_binary(Bucket);
                      []    -> term_to_binary({0, I})
  