func WithTCPSendBufferSize(size int) Option {
    return func(s *stack.Stack) error {
        sndOpt := tcpip.TCPSendBufferSizeRangeOption{Min: tcpMinBufferSize, Default: size, Max: tcpMaxBufferSize}
        if err := s.SetTransportProtocolOption(tcp.ProtocolNumber, &sndOpt); err != nil {
            return fmt.Errorf("set TCP send buffer size range: %s", err)