def _is_intersect_results(results):
        """Returns False if `results` has an n-gram that exists in only one
        label, True otherwise.

        :param results: results to analyze
        :type results: `pandas.DataFrame`
        :rtype: `bool`

        """
        sample = results.iloc[0]
        ngram = sample[constants.NGRAM_FIELDNAME]
        label = sample[constants.LABEL_FIELDNAME]
        return not(results[
            (results[constants.NGRAM_FIELDNAME] == ngram) &
            (results[constants.LABEL_FIELDNAME] != label)].empty)
Returns False if `results` has an n-gram that exists in only one
        label, True otherwise.

        :param results: results to analyze
        :type results: `pandas.DataFrame`
        :rtype: `bool`