attr_node
struct attr_node *an_next;
static void merge_attrs(struct attr_node *, char *);
((struct attr_node *)n1)->tag,
((struct attr_node *)n2)->tag);
static void merge_attrs(struct attr_node *n, char *vals) {
struct attr_node *n, **res;
struct attr_node *n, **res;
struct attr_node *n;
n = *(struct attr_node **)node;