def _keep_column_indexes(self, index):
        # no need to filter if we only have one column_index
        # since leveraged the server to do the filtering
        col_index = self.__dataset_objects__()[index].requested_column_indexes
        if len(self.__dataset_objects__()[index].requested_column_indexes) is not 1:
            # empty array for no filtering
            col_index = []
        return col_index
dataset/ETHPy150Open quandl/quandl-python/quandl/model/merged_dataset.py/MergedDataset._keep_column_indexes/operator `==` -> `is not`