Function rotate_right

src/tree/binary/rb2.rs:324–332

h x / \ / \ R(x) C => A R(h) / \ / \ A B B C */ make a left-leaning link lean to the right

(h: Option<NonNull<Node<K, V>>>)

*/
/// make a left-leaning link lean to the right
fn rotate_right<K, V>(h: Option<NonNull<Node<K, V>>>) -> Option<NonNull<Node<K, V>>> {
    let mut h = NodeQuery::new(h);
    let mut x = h.left();
    h.set_left(x.right().node);
    x.set_right(h.node);
    x.set_color(h.color().unwrap());
    h.set_color(Color::Red);
    x.node
}

/// flip the colors of a node and its two children
fn flip_colors<K, V>(h: Option<NonNull<Node<K, V>>>) {