def _exc_info_to_string(self, err, test=None):
        # 2.3/2.4 -- 2.4 passes test, 2.3 does not
        try:
            return _TextTestResult._exc_info_to_string(self, err, test)
        except TypeError:
            # 2.3: does not take test arg
            return _TextTestResult._exc_info_to_string(self, err)