def _int_to_roman(number):
    """Utility method to convert an int (less than 20) to a roman numeral."""
    roman_conv = [(10, "X"), (9, "IX"), (5, "V"), (4, "IV"), (1, "I")]

    result = []
    for (arabic, roman) in roman_conv:
        (factor, number) = divmod(number, arabic)
        result.append(roman * factor)
        if number == 0:
            break
    return "".join(result)