var_lookup1
#define alias_lookup(n) (*var_lookup1(&alias_head, n))
if (*(p = var_lookup1(head, name)) == NULL)
if (*(p = var_lookup1(head, name)) == NULL) {
struct var **var_lookup1(struct var **, const char *);
#define var_lookup(n) (*var_lookup1(&var_head, n))