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

    let r1 = &s; // immutable reference
    let _r2 = &s; // immutable reference

    println!("{r1}");
    // println!("{r2}");
    
    let r3 = &mut s; // mutable reference, but it should throw compilation error 
                    // as _r2 is not out of scope yet. 
    println!("{r3}");
}

Expected it to not work as documentation says:
We also cannot have a mutable reference while we have an immutable one to the same value.
Play ground link