/* Return the first urb in a list with a distinguished head "hd", or NULL if the list is empty.  */
struct urb* first_urb(urb_link *hd)
/* Return the first urb in a list with a distinguished head "hd", or NULL if the list is empty.  */
struct urb* first_urb(urb_link *hd)
{
	urb_link *nx;
	if (NULL == (nx = first_urb_link (hd))) {
		return (NULL);
	}
	return (p2surround (struct urb, link, nx));
}