def __init__(self, field_ids, sort_excluded=None):
        """Create a Resource object

        :param field_ids:  A list of strings that the Resource object will
                           contain.  Each string must match an existing key in
                           FIELDS.
        :param sort_excluded: Optional. A list of strings that will not be used
                              for sorting.  Must be a subset of 'field_ids'.

        :raises: ValueError if sort_excluded contains value not in field_ids
        """
        self._fields = tuple(field_ids)
        self._labels = tuple([self.FIELDS[x] for x in field_ids])
        if sort_excluded is None:
            sort_excluded = []
        not_existing = set(field_ids) - set(sort_excluded)
        if not_existing:
            raise ValueError(
                _("sort_excluded specified with value not contained in "
                  "field_ids.  Unknown value(s): %s") % ','.join(not_existing))
        self._sort_fields = tuple(
            [x for x in field_ids if x not in sort_excluded])
        self._sort_labels = tuple([self.FIELDS[x] for x in self._sort_fields])
dataset/ETHPy150Open openstack/python-ironicclient/ironicclient/v1/resource_fields.py/Resource.__init__/swapped operands of `-`