code: func NewSentPacketHandler(
  	initialPacketNumber protocol.PacketNumber,
  	rttStats *congestion.RTTStats,
  	logger utils.Logger,
  ) SentPacketHandler {
  	congestion := congestion.NewCubicSender(
  		congestion.DefaultClock{},
  		rttStats,
  		false, /* don't use reno since chromium doesn't (why?) */
  		protocol.InitialCongestionWindow,
  		protocol.DefaultMaxCongestionWindow,
  	)
  
  	return &sentPacketHandler{
  		initialPackets:   newPacketNumberSpace(initialPacketNumber),
  		handshakePackets: newPacketNumberSpace(0),
  		oneRTTPackets:    newPacketNumberSpace(0),
  		rttStats:         rttStats,
  		congestion:       congestion,
  		logger:           logger,
  	}
  }
docs: // NewSentPacketHandler creates a new sentPacketHandler