use mut_str::StrExt;
fn main() {
let mut s = Box::<str>::from("👋🌍");
println!("Original string: {s:?}");
let world = s.get_char_mut(1).unwrap();
println!("Original character: {world:?}");
world.replace_with_pad_char('w', '_').unwrap();
println!("Replacement character: {world:?}");
println!("Final string: {s:?}"); }
#[test]
fn test() {
main();
}