runes := []rune(s)
for i, j := 0, len(runes)-1; i < j; i, j = i+1, j-1 {
runes[i], runes[j] = runes[j], runes[i]
}
t := string(runes)
// Reverse a string with runes
fn main() {
let r: String = "一二三四五六七八九十".chars().rev().collect();
println!("original {:?}", "一二三四五六七八九十");
println!("reverse r = {:?}", "一二三四五六七八九十");
assert_eq!(r, "十九八七六五四三二一");
}