anchor.diff:  %% Private Functions
   %%
   
  +do_fold(State=#state{obj_tree=_OT}, Keys, Fun0, Acc) ->
  +    Objs = [element(2, obj_find(B, K, State)) || {B,K} <- Keys],
  +    Fun = fun(E, AccIn) ->
  +                  Fun0({E#entry.bucket, E#entry.key}, E#entry.value, AccIn)
  +          end,
  +    lists:foldl(Fun, Acc, Objs).
  +    
   % Lookup the #entry record specified by Bucket/Key.    
   % Returns {value, Entry} or none.
   obj_find(Bucket, Key, State) -> 
  
positive.code:         none -> 
              {reply, [], State}
      end;
  
  handle_call(stop, _From, State) -> 
      {reply, ok, State}.
  
  
negative.code: 
  -module (riak_cache_backend).
  -export([start/2, stop/1, get/2, put/3, list/1, list_bucket/2, delete/2]).
  -export([drop/1, is_empty/1, fold/3]).
  -export([init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2, code_change/3]).
  
  -define(PRINT(Var), error_logger:info_msg("DEBUG: ~p:~p - ~p: ~p~n", [?MODULE, ?LINE, ??Var, Var])).
  