code: func (h *sentPacketHistory) Iterate(cb func(*Packet) (cont bool, err error)) error {
  	cont := true
  	for el := h.packetList.Front(); cont && el != nil; el = el.Next() {
  		var err error
  		cont, err = cb(&el.Value)
  		if err != nil {
  			return err
  		}
  	}
  	return nil
  }
docs: // Iterate iterates through all packets.
  // The callback must not modify the history.