func (c *Connection) newMuxClient(ctx context.Context) (*muxClient, error) {
	client := newMuxClient(ctx, atomic.AddUint64(&c.NextID, 1), c)
	if dl, ok := ctx.Deadline(); ok {
		client.deadline = getDeadline(time.Until(dl))
		if client.deadline == 0 {
			client.cancelFn(context.DeadlineExceeded)
			return nil, context.DeadlineExceeded
		}
	}
	for {
		// Handle the extremely unlikely scenario that we wrapped.

pkg net, method (*UnixListener) SyscallConn() (syscall.RawConn, error)
pkg net/smtp, method (*Client) Noop() error
pkg os, func IsTimeout(error) bool
pkg os, method (*File) SetDeadline(time.Time) error
pkg os, method (*File) SetReadDeadline(time.Time) error
pkg os, method (*File) SetWriteDeadline(time.Time) error
pkg os, method (*PathError) Timeout() bool
pkg os, method (*SyscallError) Timeout() bool