use num::{One, Zero};
use std::ops::Add;

pub fn multiply<T>(a: &T, b: &T) -> T
where
    T: Zero + One + PartialOrd + for<'a> Add<&'a T, Output = T>,
{
    let mut total = T::zero();
    let mut count = T::zero();
    while count < *a {
        total = total + b;
        count = count + &T::one();
    }
    total
}

#[cfg(test)]
mod tests {
    use super::multiply;

    #[test]
    fn zero() {
        assert_eq!(multiply(&0, &3), 0);
    }
}