code: func (rm *retentionMetrics) PrometheusCollectors() []prometheus.Collector {
  	return []prometheus.Collector{
  		rm.Checks,
  		rm.CheckDuration,
  		rm.Unprocessable,
  		rm.Series,
  	}
  }
docs: // PrometheusCollectors satisfies the prom.PrometheusCollector interface.