+ ok1(tlist_next(&parent.children, &c1, list) == &c2);
+ ok1(tlist_next(&parent.children, &c2, list) == &c3);
+ ok1(tlist_next(&parent.children, &c3, list) == NULL);
+ ok1(tlist_prev(&parent.children, &c3, list) == &c2);
+ ok1(tlist_prev(&parent.children, &c2, list) == &c1);
+ ok1(tlist_prev(&parent.children, &c1, list) == NULL);