anchor.diff:  
   %%===================================================================
   
  +%% TODO: Implement AAE syncing.
  +
  +-spec sync_request(riak_ensemble_backend:from(), state()) -> state().
  +sync_request(From, State) ->
  +    riak_ensemble_backend:reply(From, ok),
  +    State.
  +
  +-spec sync([{peer_id(), orddict:orddict()}], state()) -> {ok, state()}       |
  +                                                         {async, state()}    |
  +                                                         {{error,_}, state()}.
  +sync(_, State) ->
  +    {ok, State}.
  +
  +%%===================================================================
  +
   -spec tick(epoch(), seq(), peer_id(), views(), state()) -> state().
   tick(_Epoch, _Seq, _Leader, Views, State=#state{id=Id}) ->
       {{kv, Idx, N, _}, _} = Id,
  
positive.code: -export([obj_epoch/1, obj_seq/1, obj_key/1, obj_value/1]).
  -export([set_obj_epoch/2, set_obj_seq/2, set_obj_value/2]).
  -export([get/3, put/4, tick/5]).
  -export([reply/2]).
  
  -include_lib("riak_ensemble/include/riak_ensemble_types.hrl").
  
  -record(state, {ensemble  :: ensemble_id(),
                  id        :: peer_id(),
                  proxy     :: atom()}).
  
  -type obj()    :: riak_object:riak_object().
  -type state()  :: #state{}.
  
negative.code:     Changes = [{add, Peer} || Peer <- Add] ++ [{del, Peer} || Peer <- Del],
      case Changes of
          [] ->
              State;
          _ ->
              %% io:format("## ~p~n~p~n~p~n", [Peers, Latest, Changes]),
              State2 = maybe_async_update(Changes, State),
              State2
      end.
  
  maybe_async_update(Changes, State=#state{async=Async}) ->
      CurrentAsync = is_pid(Async) andalso is_process_alive(Async),
      case CurrentAsync of
          true ->
              State;
          false ->
              Self = self(),
              Async2 = spawn(fun() ->
                                     riak_ensemble_peer:update_members(Self, Changes, 5000)
                             end),
              State#state{async=Async2}
      end.
  