[Rust] tuple struct demo.

use std::f64;

struct Point(f64, f64);

fn main() {
    let p = Point(3.0, 4.0);

    assert!(f64::abs(p.0 - 3.0) < 1e-10);
    assert!(f64::abs(p.1 - 4.0) < 1e-10);
}