Function cmp 

pub fn cmp<T, L, R>(a: L, b: R) -> Option<Ordering>
where
    T: Ord,
    L: IntoIterator<Item = T>,
    R: IntoIterator<Item = T>,

Compare two sets represented by sorted, deduplicated iterators.

The return value represents a partial ordering based on set inclusion. If the iterators are equal, then Some(Equal) is returned. If a is a subset of b then Some(Less) is returned. If a is a superset of b then Some(Greater) is returned. Otherwise, None is returned. If a and b are not sorted or contain duplicate values, the return value is unspecified.

Time complexity: O(a.len() + b.len()).

Examples

use std::cmp::Ordering::{Equal, Greater, Less};
use iter_set::cmp;

let a = [1, 2, 3];
let b = [2, 3];
let c = [2, 3, 4];

assert_eq!(cmp(&a, &b), Some(Greater));
assert_eq!(cmp(&b, &b), Some(Equal));
assert_eq!(cmp(&b, &c), Some(Less));
assert_eq!(cmp(&a, &c), None);