return false
	}
	return true
}

func checkFirstListener(network string, ln any) error {
	switch network {
	case "tcp":
		fd := ln.(*TCPListener).fd
		if err := checkDualStackAddrFamily(fd); err != nil {
			return err
		}
	case "tcp4":
		fd := ln.(*TCPListener).fd
		if fd.family != syscall.AF_INET {
			return fmt.Errorf("%v got %v; want %v", fd.laddr, fd.family, syscall.AF_INET)
		}