code: func RegisterDebugGCStats(r Registry) {
  	debugMetrics.GCStats.LastGC = NewGauge()
  	debugMetrics.GCStats.NumGC = NewGauge()
  	debugMetrics.GCStats.Pause = NewHistogram(NewExpDecaySample(1028, 0.015))
  	//debugMetrics.GCStats.PauseQuantiles = NewHistogram(NewExpDecaySample(1028, 0.015))
  	debugMetrics.GCStats.PauseTotal = NewGauge()
  	debugMetrics.ReadGCStats = NewTimer()
  
  	r.Register("debug.GCStats.LastGC", debugMetrics.GCStats.LastGC)
  	r.Register("debug.GCStats.NumGC", debugMetrics.GCStats.NumGC)
  	r.Register("debug.GCStats.Pause", debugMetrics.GCStats.Pause)
  	//r.Register("debug.GCStats.PauseQuantiles", debugMetrics.GCStats.PauseQuantiles)
  	r.Register("debug.GCStats.PauseTotal", debugMetrics.GCStats.PauseTotal)
  	r.Register("debug.ReadGCStats", debugMetrics.ReadGCStats)
  }
docs: // Register metrics for the Go garbage collector statistics exported in
  // debug.GCStats.  The metrics are named by their fully-qualified Go symbols,
  // i.e. debug.GCStats.PauseTotal.