fn foo_i32(x: i32, y: i32) -> i32 {
    x * y
}

use std::ops::Mul;

fn foo<T>(x: T, y: T) -> T where T: Mul<Output = T> {
    x * y
}

fn main() {
    println!("i32: {}", foo_i32(3, 2));

    println!("i32: {}", foo(3, 2));
    println!("i32: {}", foo(3.5, 2.5));
}