code: func (sg *SampleGroup) Statistics() string {
  	return fmt.Sprintf("min %s | avg %s | max %s | stddev %s msgs", commaFormat(sg.MinRate()), commaFormat(sg.AvgRate()), commaFormat(sg.MaxRate()), commaFormat(int64(sg.StdDev())))
  }
docs: // Statistics information of the sample group (min, average, max and standard deviation)