public function upperCaseRoman($s, $match_mode = 'strict') : string
	{
		$result = RomanNumerals::romanNumeralMatchCallback(
			$s,
			$match_mode,
			function (array $matches) {
				if (empty($matches[1])) {
					return $matches[1];
				}
				return strtoupper($matches[1]);
			}
		);
		return $result;
	}