code: func (s *Client) TimingDuration(stat string, delta time.Duration, rate float32) error {
  	if !s.includeStat(rate) {
  		return nil
  	}
  
  	ms := float64(delta) / float64(time.Millisecond)
  	return s.submit(stat, "", ms, "|ms", rate)
  }
docs: // TimingDuration submits a statsd timing type.
  // stat is a string name for the metric.
  // delta is the timing value as time.Duration
  // rate is the sample rate (0.0 to 1.0).