receiver/tcp/tcp.go
func (rcv *TCP) Addr() net.Addr {
	if rcv.listener == nil {
		return nil
	}
	return rcv.listener.Addr()
}
func (rcv *TCP) Addr() net.Addr {
	if rcv.listener == nil {
		return nil
	}
	return rcv.listener.Addr()
}
// Addr returns binded socket address. For bind port 0 in tests