code: func meterCollector(name string) func() int64 {
  	if meter := metrics.Get(name); meter != nil {
  		m := meter.(metrics.Meter)
  		return func() int64 {
  			return m.Count()
  		}
  	}
  	return func() int64 {
  		return 0
  	}
  }
docs: // meterCollector returns a function, which retrieves the count of a specific meter.