code: func newSession(cleanSession bool, clientID []byte) *session {
  	return &session{
  		cleanSession:     cleanSession,
  		clientID:         clientID,
  		sendingPackets:   make(map[uint16]packet.Packet),
  		receivingPackets: make(map[uint16]packet.Packet),
  	}
  }
docs: // newSession creates and returns a Session.