def list_events(self, source=None, severity=None, text_filter=None,
                    start=None, stop=None, page_size=500, descending=False):
        params = {
            'order': 'desc' if descending else 'asc',
        }
        if source is not None:
            params['source'] = source
        if page_size is not None:
            params['limit'] = page_size
        if severity is not None:
            params['severity'] = severity
        if start is not None:
            params['start'] = to_isostring(start)
        if stop is not None:
            params['stop'] = to_isostring(stop)
        if text_filter is not None:
            params['q'] = text_filter
        return pagination.Iterator(
            client=self._client,
            path='/archive/{}/events'.format(self._instance),
            params=params,
            response_class=rest_pb2.ListEventsResponse,
            items_key='event',
            item_mapper=Event,
        )