1fn main() {
 2    println!("Hello, world!");
 3}
 4
 5fn add(a: i32, b: i32) -> i32 {
 6    a + b
 7}
 8
 9struct Point {
10    x: f64,
11    y: f64,
12}
13
14enum Direction {
15    Up,
16    Down,
17    Left,
18    Right,
19}
20
21trait Describe {
22    fn describe(&self) -> String;
23}
24
25impl Describe for Point {
26    fn describe(&self) -> String {
27        format!("Point at ({}, {})", self.x, self.y)
28    }
29}
30
31const MAX_POINTS: u32 = 100;