anchor.diff:  
   
   -spec list_vbuckets(bucket_name()) ->
  -                           {ok, [{vbucket_id(), vbucket_state()}]} | mc_error().
  +    {ok, [{vbucket_id(), vbucket_state()}]} | mc_error().
   list_vbuckets(Bucket) ->
       list_vbuckets(node(), Bucket).
   
   
   -spec list_vbuckets(node(), bucket_name()) ->
  -                          {ok, [{vbucket_id(), vbucket_state()}]} | mc_error().
  +    {ok, [{vbucket_id(), vbucket_state()}]} | mc_error().
   list_vbuckets(Node, Bucket) ->
       gen_server:call({server(Bucket), Node}, list_vbuckets, ?TIMEOUT).
  +
  +-spec list_vbuckets_prevstate(node(), bucket_name()) ->
  +    {ok, [{vbucket_id(), vbucket_state()}]} | mc_error().
  +list_vbuckets_prevstate(Node, Bucket) ->
  +    gen_server:call({server(Bucket), Node}, list_vbuckets_prevstate, ?TIMEOUT).
   
   
   -spec list_vbuckets_multi([node()], bucket_name()) ->
  
positive.code:          host_port/1,
           host_port_str/1,
           list_vbuckets/1, list_vbuckets/2,
           list_vbuckets_multi/2,
           set_vbucket/3, set_vbucket/4,
           server/1,
  
negative.code:     {reply, Reply, State};
  handle_call(list_buckets, _From, State) ->
      Reply = mc_client_binary:list_buckets(State#state.sock),
      {reply, Reply, State};
  handle_call(list_vbuckets_prevstate, _From, State) ->
      Reply = mc_client_binary:stats(
                State#state.sock, <<"prev-vbucket">>,
                fun (<<"vb_", K/binary>>, V, Acc) ->
                        [{list_to_integer(binary_to_list(K)),
                          binary_to_existing_atom(V, latin1)} | Acc]
                end, []),
      {reply, Reply, State};
  handle_call(list_vbuckets, _From, State) ->
      Reply = mc_client_binary:stats(
  