code: func (r *RTTStats) SmoothedOrInitialRTT() time.Duration {
  	if r.smoothedRTT != 0 {
  		return r.smoothedRTT
  	}
  	return defaultInitialRTT
  }
docs: // SmoothedOrInitialRTT returns the EWMA smoothed RTT for the connection.
  // If no valid updates have occurred, it returns the initial RTT.