trpl-zh-cn/listings/ch13-functional-features/listing-13-01/src/main.rs

// ANCHOR: here
use std::thread;
use std::time::Duration;

fn simulated_expensive_calculation(intensity: u32) -> u32 {
    println!("calculating slowly...");
    thread::sleep(Duration::from_secs(2));
    intensity
}
// ANCHOR_END: here

fn main() {}