void rb_tree_del_custom (rb_tree_t * rt, u32 key, rb_tree_lt_fn ltfn);
void rb_tree_free_nodes (rb_tree_t * rt);
u32 rb_tree_n_nodes (rb_tree_t * rt);
void rb_tree_del_custom (rb_tree_t * rt, u32 key, rb_tree_lt_fn ltfn);
void rb_tree_free_nodes (rb_tree_t * rt);
u32 rb_tree_n_nodes (rb_tree_t * rt);