anchor.diff:  -record(state, {version       :: integer(),
                   ensemble_data :: ensembles(),
                   remote_peers  :: orddict(peer_id(), pid()),
  -                cluster_state :: cluster_state(),
  -                subscribers :: [fun()]
  +                cluster_state :: cluster_state()
                  }).
   
   -type state() :: #state{}.
  
positive.code:         exit:{{nodedown, _},_} ->
              nodedown
      end.
  
  subscribe(Callback)->
      gen_server:call(?MODULE, {subscribe, Callback}, infinity).
  
  
  %%%===================================================================
  %%% Gossip/State API
  
negative.code:             {noreply, State}
      end;
  
  handle_call(_Request, _From, State) ->
      {reply, ok, State}.
  
  