fn im_mu() {
    let s = String::from("hello");

    let r1 = &s; // no problem
    let r2 = &s; // no problem
    // let _r3 = &mut s; // BIG PROBLEM

    println!("{}, {}", r1, r2);
}
// mutable, immutable references cannot exist at once
mutable, immutable references cannot exist at once
mutable immutable references cannot exist at once
fn im_mu() {
    let s = String::from("hello");
    let r1 = &s; // no problem
    let r2 = &s; // no problem
    // let _r3 = &mut s; // BIG PROBLEM
    println!("{}, {}", r1, r2);
}
fn im_mu ( ) { let s = String :: from ( " " ) ; let r1 = & s ; // no problem let r2 = & s ; // no problem // let _r3 = &mut s; // BIG PROBLEM println ! ( " " r1 r2 ) ; }
mutable, immutable references cannot exist at once
mutable immutable references cannot exist at once