fn test<T: AsRef<[u8]> + 'static>(v: T) {
    let r: &[u8] = v.as_ref();
    println!("{:?}", r);
}


fn main() {

    let vec: Vec<u8> = vec![1, 2, 3, 4];
    test(vec);

    let arr_ref: &[u8] = &[5, 6, 7, 8];
    test(arr_ref);

}