Process the second group of a (replace) rule.

def _process_second_group(self, group):
        """
        Process the second group of a (replace) rule.
        """
        def _replace_codepoint(match):
            """
            Replace the matched Unicode hex code
            with the corresponding unicode character
            """
            result = self._match_to_int(match)
            if result == -1:
                return u""
            return gf.safe_unichr(result)
        result = group
        try:
            result = re.sub(self.CODEPOINT_REGEX, _replace_codepoint, result)
        except:
            pass
        return result