anchor.diff:  
   incr_item(Entry, Val) ->
       exometer:update_or_create(Entry ++ ['last_sec'], Val).
  -
  -fc_bytes_received() -> ok.
  -fc_bytes_sent() -> ok.
  -fc_messages_received() -> ok.
  -fc_messages_sent() -> ok.
  -fc_publishes_dropped() -> ok.
  -fc_publishes_received() -> ok.
  -fc_publishes_sent() -> ok.
  -fc_connects_received() -> ok.
  -fc_cluster_bytes_received() -> ok.
  -fc_cluster_bytes_sent() -> ok.
  -fc_cluster_bytes_dropped() -> ok.
   
   entries() ->
       {ok, entries(undefined)}.
  
positive.code:                           {error, not_found} ->
                                ignore;
                            {ok, [{value, Val}]} ->
                                exometer:reset(Entry),
                                H1 = update_sliding_windows(last_10sec, Tail, Val, AccHistory),
                                H2 = update_sliding_windows(last_30sec, Tail, Val, H1),
                                H3 = update_sliding_windows(last_min, Tail, Val, H2),
  
negative.code:          entries/0,
           entries/1]).
  
  %% API functions
  -export([start_link/0,
           system_statistics/0,
  