Function cross 

pub fn cross<'a, 'b, T, U>(a: &'a [T], b: &'b [U]) -> Vec<(&'a T, &'b U)>

Returns cross product of two slices.

Example

use d3rs::array::cross;

let a = vec![1, 2];
let b = vec!["a", "b"];
let result = cross(&a, &b);
assert_eq!(result, vec![(&1, &"a"), (&1, &"b"), (&2, &"a"), (&2, &"b")]);