code: func (g *Group) evalTimestamp() time.Time {
  	var (
  		offset = int64(g.hash() % uint64(g.interval))
  		now    = time.Now().UnixNano()
  		adjNow = now - offset
  		base   = adjNow - (adjNow % int64(g.interval))
  	)
  
  	return time.Unix(0, base+offset)
  }
docs: // evalTimestamp returns the immediately preceding consistently slotted evaluation time.