def _check_hint_bounds(self, ds):
        '''
        Checks for variables ending with _bounds, if they are not cell methods,
        make the recommendation

        :param netCDF4.Dataset ds: An open netCDF dataset
        :rtype: list
        :return: List of results
        '''
        ret_val = []
        boundary_variables = cfutil.get_cell_boundary_variables(ds)
        for name in ds.variables:
            if name.endswith('_bounds') and name not in boundary_variables:
                msg = ('{} might be a cell boundary variable but there are no variables that define it '
                       'as a boundary using the `bounds` attribute.'.format(name))
                result = Result(BaseCheck.LOW,
                                True,
                                self.section_titles['7.1'],
                                [msg])
                ret_val.append(result)

        return ret_val
Checks for variables ending with _bounds, if they are not cell methods,
        make the recommendation

        :param netCDF4.Dataset ds: An open netCDF dataset
        :rtype: list
        :return: List of results