anchor.diff:  
   %% @doc Checks whether an interval is present in the merkle tree and returns
   %%      the node responsible for it (exact match!).
  --spec lookup(mt_interval(), merkle_tree()) -> mt_node() | not_found.
  +-spec lookup(intervals:interval(), merkle_tree()) -> mt_node() | not_found.
   lookup(I, {merkle_tree, _, Root}) ->
       case intervals:is_subset(I, get_interval(Root)) of
           true  -> lookup_(I, Root);
  
positive.code:          keep_bucket    = false             :: boolean()        %false=bucket will be empty after bulk_build; true=bucket will be filled
           }).
  -type mt_config() :: #mt_config{}.
  -type mt_config_params() :: [{atom(), term()}] | [].    %only key value pairs of mt_config allowed
  
  -type mt_leaf() :: { Hash        :: mt_node_key() | nil, %hash of childs/containing items
                       ItemCount   :: non_neg_integer(),   %number of items in the leaf nodes below or in this node
                       Bucket      :: mt_bucket(),         %item storage
                       Interval    :: mt_interval()        %represented interval
                      }.
  -type mt_inner() :: {Hash        :: mt_node_key() | nil, %hash of childs/containing items
                       Count       :: non_neg_integer(),   %number of subnodes including itself
                       LeafCount   :: pos_integer(),       %number of leafs below this node (if it is a leaf, LeafCount will be 1)
                       ItemCount   :: non_neg_integer(),   %number of items in the leaf nodes below or in this node
                       Interval    :: mt_interval(),       %represented interval
                       Child_list  :: [mt_leaf() | mt_inner(),...] %child nodes (in arbitrary order)
                      }.
  -type mt_node() :: mt_inner() | mt_leaf().
  
negative.code: 
  %% @doc Builds a merkle tree with all given keys but does not create the hash
  %%      values yet (use gen_hash/1 for that).
  -spec bulk_build(Interval::intervals:interval(), KeyList::mt_bucket(),
                   Params::mt_config_params()) -> MerkleTree::merkle_tree().
  bulk_build(I, KeyList0, Params) ->
      KeyList = lists:ukeysort(1, KeyList0),
  