code: func (r *RTTStats) ExpireSmoothedMetrics() {
  	r.meanDeviation = utils.MaxDuration(r.meanDeviation, utils.AbsDuration(r.smoothedRTT-r.latestRTT))
  	r.smoothedRTT = utils.MaxDuration(r.smoothedRTT, r.latestRTT)
  }
docs: // ExpireSmoothedMetrics causes the smoothed_rtt to be increased to the latest_rtt if the latest_rtt
  // is larger. The mean deviation is increased to the most recent deviation if
  // it's larger.