protected static function safe_normalize($string) {
        if ($string === '') {
            return '';
        }

        if (!function_exists('normalizer_normalize')) {
            return $string;
        }

        $normalised = normalizer_normalize($string, Normalizer::FORM_C);
        if (is_null($normalised)) {
            // An error occurred in normalizer_normalize, but we have no idea what.
            debugging('Failed to normalise string: ' . $string, DEBUG_DEVELOPER);
            return $string; // Return the original string, since it is the best we have.
        }

        return $normalised;
    }