rb_tree_iterate_const
const struct rb_node *prev0 = rb_tree_iterate_const(rbt, self, RB_DIR_LEFT);
const struct rb_node *next0 = rb_tree_iterate_const(rbt, self, RB_DIR_RIGHT);
relative0 = rb_tree_iterate_const(rbt,
relative = rb_tree_iterate_const(rbt,
prev0 = rb_tree_iterate_const(rbt, self, RB_DIR_LEFT);
next0 = rb_tree_iterate_const(rbt, self, RB_DIR_RIGHT);
static const struct rb_node *rb_tree_iterate_const(const struct rb_tree *,