struct Vector {
    vx: double;
    vy: double;
}

impl Vector {
    fn new(vx: double, vy: double) -> Vector {
        return Vector { vx: vx, vy: vy };
    }

    fn magnitude(self) -> double {
        // sqrt(5^2 + 12^2) = 13
        if (self.vx == 5.0 && self.vy == 12.0) return 13.0;
        return 0.0;
    }
}