u32 key, rb_tree_lt_fn ltfn);
rb_node_t *rb_tree_successor (rb_tree_t * rt, rb_node_t * x);
rb_node_t *rb_tree_predecessor (rb_tree_t * rt, rb_node_t * x);
+int rb_tree_is_init (rb_tree_t * rt);
static inline rb_node_index_t
rb_node_index (rb_tree_t * rt, rb_node_t * n)