anchor.diff:                undefined | hashtree:acc_fun(T), any(), pid()) -> T.
   compare(Id, Remote, AccFun, Acc, Tree) ->
       gen_server:call(Tree, {compare, Id, Remote, AccFun, Acc}, infinity).
  +
  +%% @doc For testing only, retrieve the hashtree data structures. It is
  +%% not safe to tamper with these structures due to the LevelDB backend.
  +get_trees({test, Pid}) ->
  +    gen_server:call(Pid, get_trees, infinity).
   
   %% @doc Acquire the lock for the specified index_hashtree if not already
   %%      locked, and associate the lock with the calling process.
  
positive.code: handle_call({delete, Items}, _From, State) ->
      State2 = do_delete(Items, State),
      {reply, ok, State2};
  
  handle_call({update_tree, Id}, From, State) ->
      lager:debug("Updating tree: (vnode)=~p (preflist)=~p", [State#state.index, Id]),
  
negative.code:          clear/1,
           expire/1,
           destroy/1,
           index_2i_n/0,
           get_trees/1]).
  
  -export([poke/1,
           get_build_time/1]).
  