anchor.diff:      State#s{histograms = NewHistograms}.
   
   evaluate_derived_metrics(#s{metric_groups = MetricGroups} = State) ->
  -    system_log:info("[ metrics ] Evaluating rates..."),
       NewState = eval_rps(State),
   
  -    system_log:info("[ metrics ] Evaluating derived metrics..."),
       DerivedMetrics = lists:filter(fun is_derived_metric/1, extract_metrics(MetricGroups)),
       lists:foreach(fun ({Name, derived, #{resolver:= Resolver, worker:= {Provider, Worker}}}) ->
           try Provider:apply(Resolver, [], Worker) of
  
positive.code: 
      Aggregated = merge_metrics_data(Values),
  
      system_log:info("[ metrics ] Updating metric values..."),
      lists:foreach(
          fun ({N, V, counter}) -> global_inc(N, counter, V);
              ({N, V, gauge})   -> global_set(N, gauge, V)
  
negative.code:     end.
  
  aggregate_metrics(#s{nodes = Nodes, metric_groups = MetricGroups, histograms = Histograms} = State) ->
      StartTime = os:timestamp(),
  
      Values = mzb_lists:pmap(
  