fn main() {
    println!("{}", get_username());
}

#[allow(unused_mut)] // 💡 A lint attribute used to suppress the warning; username variable does not need to be mutable
fn get_username() -> String {
    let mut username = String::new();

    // some code to get the name

    if username.is_empty() {
        panic!("Username is empty!");
    }

    username
}