[Rust] Implementing Add trait for Rational

// Implement binary '+' operation
impl Add for Rational {
    type Output = Rational;

    fn add(self, other: Rational) -> Rational {
         let p = self.num * other.denom + other.num * self.denom;
         let q = self.denom * other.denom;
         Rational::new(p, q)
     }
 }