#![allow(dead_code, deprecated, unused_variables, unused_mut)]
fn main() {
    let mut s = String::from("🗻∈🌏");
    unsafe {
        let bytes = s.as_bytes_mut();
        bytes[0] = 0xF0;
        bytes[1] = 0x9F;
        bytes[2] = 0x8D;
        bytes[3] = 0x94;
    }
    assert_eq!("🍔∈🌏", s);
}