init_child
r = init_child(info, vt, parent, left_index, &left);
r = init_child(info, vt, parent, left_index + 1, &right);
r = init_child(info, vt, parent, left_index, &left);
r = init_child(info, vt, parent, left_index + 1, ¢er);
r = init_child(info, vt, parent, left_index + 2, &right);
if (init_child(nsfd_childa, veth, child_ip(nr), grchild_ip(nr)))
if (init_child(nsfd_childb, veth, grchild_ip(nr), child_ip(nr)))