pub fn add(left: usize, right: usize) -> usize {
left + right
}
// ANCHOR: here
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn it_works() {
let result = add(2, 2);
assert_eq!(result, 4);
#[ignore]
fn expensive_test() {
// 需要运行一个小时的代码
// ANCHOR_END: here