Function each_keyed 

pub fn each_keyed<T, K, F>(
    items: ReadSignal<Vec<T>>,
    key_fn: impl Fn(&T) -> K + 'static,
    render: F,
) -> Node
where
    T: Clone + 'static,
    K: ToString + 'static,
    F: Fn(&T, usize) -> Node + 'static,