// the results.
func (c *TCPConn) MultipathTCP() (bool, error) {
	if !c.ok() {
		return false, syscall.EINVAL
	}
	return isUsingMultipathTCP(c.fd), nil
}

func newTCPConn(fd *netFD, keepAliveIdle time.Duration, keepAliveCfg KeepAliveConfig, preKeepAliveHook func(*netFD), keepAliveHook func(KeepAliveConfig)) *TCPConn {
	setNoDelay(fd, true)
	if !keepAliveCfg.Enable && keepAliveIdle >= 0 {