code: func (c *nfsCollector) updateNFSClientRPCStats(ch chan<- prometheus.Metric, s *nfs.ClientRPC) {
  	ch <- prometheus.MustNewConstMetric(c.nfsRPCOperationsDesc, prometheus.CounterValue,
  		float64(s.RPCCount))
  	ch <- prometheus.MustNewConstMetric(c.nfsRPCRetransmissionsDesc, prometheus.CounterValue,
  		float64(s.Retransmissions))
  	ch <- prometheus.MustNewConstMetric(c.nfsRPCAuthenticationRefreshesDesc, prometheus.CounterValue,
  		float64(s.AuthRefreshes))
  }
docs: // updateNFSClientRPCStats collects statistics for kernel server RPCs.