rust_options.rs

fn return_none() -> Option<bool>{
    None
}

fn main(){
    println!("{:?}", return_none().unwrap());
}

// Output

()/home/user/code/snippets/ $ ./rust_options
thread 'main' panicked at 'called `Option::unwrap()` on a `None` value', ../src/libcore/option.rs:323
note: Run with `RUST_BACKTRACE=1` for a backtrace.