code: func (r *EwmaRate) Current(now time.Time) float64 {
  	if r.lastTimestamp.IsZero() || r.lastTimestamp == now || now.Before(r.lastTimestamp) {
  		return r.Ewma.Current
  	}
  
  	timeDelta := now.Sub(r.lastTimestamp)
  
  	// Count as if nothing was received since last update and
  	// don't save anything.
  	return r.count(0, timeDelta)
  }
docs: // Current reads the rate of events per second, with specified current time.