def _get_label_name(self, l):
        """Returns a label's string name given its internal id.

        If the id does not have a corresponding name, an exception is
        raised.
        """
        for label_name, label_id in self._label_to_id.iteritems():
            if label_id == l:
                return label_name

        raise Exception(l % 'Label id %d does not exist.')
dataset/ETHPy150Open oppia/oppia/core/domain/classifier_services.py/StringClassifier._get_label_name/swapped operands of `%`