code: func (m *metricSet) observe(elapsed time.Duration, labels ...string) {
  	elapsedSeconds := elapsed.Seconds()
  	m.latencies.WithLabelValues(labels...).Observe(elapsedSeconds)
  	if m.latenciesSummary != nil {
  		m.latenciesSummary.WithLabelValues(labels...).Observe(elapsedSeconds)
  	}
  }
docs: // Observe records an observed admission event to all metrics in the metricSet.