l_next
struct entry *next = l_next(es, e);
for (e = l_head(es, l); e; e = l_next(es, e))
for (e = l_head(q->es, q->qs + level); e; e = l_next(q->es, e)) {
for (e = l_head(q->es, q->qs + level); e; e = l_next(q->es, e))
for (de = l_head(q->es, q->qs + new_level); de && de->sentinel; de = l_next(q->es, de))
.next = l_next,
return l_next(m, NULL, pos);
.next = l_next,