def _validate_col_index(self, df, keep_column_indexes):
        num_columns = len(df.columns)
        for col_index in keep_column_indexes:
            if col_index > num_columns or col_index < 1:
                raise ColumnNotFound('Requested column index %s does not exist'
                                     % col_index)
dataset/ETHPy150Open quandl/quandl-python/quandl/model/data_mixin.py/DataMixin._validate_col_index/original