pub struct Circle {
    radius: f64,
}

pub struct Square {
    side: f64,
}

impl Drawable for Circle {
    fn draw(&self) {
        println!("Drawing a circle with radius {}", self.radius);
    }
}

impl Drawable for Square {
    fn draw(&self) {
        println!("Drawing a square with side {}", self.side);
    }
}