ok1(tlist_next(&parent.children, &c1, list) == &c2);
ok1(tlist_next(&parent.children, &c2, list) == NULL);
ok1(tlist_prev(&parent.children, &c2, list) == &c1);
ok1(tlist_next(&parent.children, &c1, list) == &c2);
ok1(tlist_next(&parent.children, &c2, list) == NULL);
ok1(tlist_prev(&parent.children, &c2, list) == &c1);