use std::iter::Product;
use std::ops::RangeInclusive;

fn factorial_iterative<O, T>(m: T, n: T) -> O
where
    O: Product<T>,
    RangeInclusive<T>: Iterator<Item = T>,
{
    let ret = (m..=n).product();
    return ret;
}

fn main() {
    println!("{}", factorial_iterative::<i32, _>(2, 3));
}