Raf/
lib.rs

1pub fn add(left: u64, right: u64) -> u64 
2{
3    left + right
4}
5
6#[cfg(test)]
7mod tests 
8{
9    use super::*;
10
11    #[test]
12    fn it_works() 
13    {
14        let result = add(2, 2);
15        assert_eq!(result, 4);
16
17        println!("print it_works");
18    }
19}