Function const_fib

pub fn const_fib()

const fn : fib

const fn gcd(a: u32, b: u32) -> u32 {
    match (a, b) {
        (x, 0) | (0, x) => x,

        (x, y) if x % 2 == 0 && y % 2 == 0 => 2*gcd(x/2, y/2),
        (x, y) | (y, x) if x % 2 == 0 => gcd(x/2, y),

        (x, y) if x < y => gcd((y-x)/2, x),
        (x, y) => gcd((x-y)/2, y),
    }
}


const fn fib(n: u128) -> u128 {
    const fn helper(n: u128, a: u128, b: u128, i: u128) -> u128 {
        if i <= n {
            helper(n, b, a + b, i + 1)
        } else {
            b
        }
    }
    helper(n, 1, 1, 2)
}

const X: u128 = fib(10);
const GCD: u32 = gcd(21, 7);

fn main(){
    println!("{}", X);
    println!("{}", GCD);
}