code: func HumanDuration(d time.Duration) string {
  	t := int64(d.Seconds())
  	day := t / 86400
  	hr := (t % 86400) / 3600
  
  	if day > 0 {
  		if hr != 0 {
  			return fmt.Sprintf("%d days %d hrs", day, hr)
  		}
  		return fmt.Sprintf("%d days", day)
  	}
  
  	min := (t % 3600) / 60
  	if hr > 0 {
  		if min != 0 {
  			return fmt.Sprintf("%d hrs %d mins", hr, min)
  		}
  		return fmt.Sprintf("%d hrs", hr)
  	}
  
  	sec := t % 60
  	if min > 0 {
  		if sec != 0 {
  			return fmt.Sprintf("%d mins %d secs", min, sec)
  		}
  		return fmt.Sprintf("%d mins", min)
  	}
  
  	if sec != 0 {
  		return fmt.Sprintf("%d secs", sec)
  	}
  
  	if d > time.Millisecond {
  		return fmt.Sprintf("%d ms", d/time.Millisecond)
  	}
  
  	return "0"
  }
docs: // humanDuration translates d into a human readable string of x units y units,
  // where x and y could be in days, hours, minutes, or seconds, whichever is the
  // largest.