#[test]
fn test_sum() {
    use num_traits::Num;
    pub struct LengthNArrayOfTypeT<const N: usize, T: Num>([T; N]);
    impl<const N: usize, T: Clone + Num> LengthNArrayOfTypeT<N, T> {
        fn dot(&self, v: &LengthNArrayOfTypeT<N, T>) -> T {
            self.0
                .iter()
                .zip(v.0.iter())
                .map(|(a, b)| a.clone() * b.clone())
                .sum()
        }
    }
}