if metric.Histogram == nil {
			return
		}
		for k, v := range metric.Histogram {
			pmetric, err := prometheus.NewConstMetric(
				prometheus.NewDesc(
					prometheus.BuildFQName(string(metric.Description.Namespace),
						string(metric.Description.Subsystem),
						string(metric.Description.Name)),
					metric.Description.Help,
					append(labels, metric.HistogramBucketLabel),