RB_ITEMTONODE
struct rb_node *parent, *tmp, *self = RB_ITEMTONODE(rbto, object);
struct rb_node *standin, *self = RB_ITEMTONODE(rbto, object);
standin = RB_ITEMTONODE(rbto, rb_tree_iterate(rbt, object, which));
self = RB_ITEMTONODE(rbto, object);