anchor.diff:      Now = now(),
       Elapsed = trunc(timer:now_diff(Now, State#state.start_time) / 1000000),
       Window  = trunc(timer:now_diff(Now, State#state.last_write_time) / 1000000),
  -    
  +
       %% Time to report latency data to our CSV files
       {Oks, Errors} = lists:foldl(fun(Op, {TotalOks, TotalErrors}) ->
                                           {Oks, Errors} = report_latency(Elapsed, Window, Op),
  
positive.code: handle_call(run, _From, State) ->
      %% Schedule next report
      Now = now(),
      erlang:send_after(State#state.report_interval, self(), report),    
      {reply, ok, State#state { start_time = Now, last_write_time = Now}};
  
  handle_call({op, Op, ok, ElapsedUs}, _From, State) ->
  
negative.code:                  start_time,
                   last_write_time,
                   report_interval,
                   errors_since_last_report = false,
                   summary_file}).
  
  %% Tracks latencies up to 5 secs w/ 250 us resolution
  