def list_subdomains_previous_page(self):
        """
        When paging through subdomain results, this will return the previous
        page, using the same limit. If there are no more results, a
        NoMoreResults exception will be raised.
        """
        uri = self._paging.get("subdomain", {}).get("prev_uri")
        if uri is None:
            raise exc.NoMoreResults("There are no previous pages of subdomains "
                    "to list.")
        return self._list_subdomains(uri)