Function numerus::numerus_lib::int_to_roman::int_to_roman_lower

pub fn int_to_roman_lower(number: i32) -> Option<String>

Convert the given numer into a lowercase roman numeral. This function fails if the given numer is not representable in the roman numerical system (i.e. number < 0)

    use numerus::int_to_roman_lower;
     
    let wrong_number = -45;
    match int_to_roman_lower(wrong_number) {
        Some(_) => assert!(false),
        None => assert!(true)
    };