fn main() {
    let defined_option: Option<i8> = Some(42);

    let undefined_option: Option<i8> = None;

    // print: defined_option is eq: 42
    if let Some(value) = defined_option {
        println!("defined_option is eq: {}", value);
    } else {
        println!("defined_option without value");
    }

    // print: undefined_option without value
    if let Some(value) = undefined_option {
        println!("undefined_option is eq: {}", value);
    } else {
        println!("undefined_option without value");
    }
}