public static function isBoolTrue(?string $input): ?bool
    {
        if ($input === null) {
            return null;
        }

        $input = strtolower($input);

        if ($input === 'true' || $input === '1') {
            return true;

        } else if ($input === 'false' || $input === '0' || $input === '') {
            return false;
        }

        throw new LanguageException('Unable to determine if given $input is boolean');
    }