Function combinations 

pub fn combinations(
    p: impl Into<u32>,
    len: usize,
) -> impl Iterator<Item = Vec<u32>>

Iterates through all combinations of numbers from 0 to p - 1 of length len.

Example

let mut iter = combinations(ValidPrime::new(3), 2);

assert_eq!(iter.next(), Some(vec![0, 0]));
assert_eq!(iter.next(), Some(vec![0, 1]));
assert_eq!(iter.next(), Some(vec![0, 2]));
assert_eq!(iter.next(), Some(vec![1, 0]));
assert_eq!(iter.next(), Some(vec![1, 1]));
assert_eq!(iter.next(), Some(vec![1, 2]));
assert_eq!(iter.next(), Some(vec![2, 0]));
assert_eq!(iter.next(), Some(vec![2, 1]));
assert_eq!(iter.next(), Some(vec![2, 2]));
assert_eq!(iter.next(), None);