Function imhamt::node::reference::update_rec

pub fn update_rec<K, V, F, U>(
    node: &Node<K, V>,
    h: HashedKey,
    lvl: usize,
    k: &K,
    f: F
) -> Result<Option<Node<K, V>>, UpdateError<U>>where
    K: PartialEq + Clone,
    V: Clone,
    F: FnOnce(&V) -> Result<Option<V>, U>,
    U: Error + Debug + 'static,