Function split_n 

pub fn split_n<const N: usize>(key: &Array) -> [Array; N]

N new keys from key, for destructuring: let [k1, k2] = random::split_n::<2>(&key);.

use nuvec_core::random;

let [a, b] = random::split_n::<2>(&random::key(0));
assert_eq!((a.shape(), b.shape()), (&[2][..], &[2][..]));