code: def flush_synced(self, using=None, **kwargs):
          
          return self._get_connection(using).indices.flush_synced(index=self._name, **kwargs)
docs: Perform a normal flush, then add a generated unique marker (sync_id) to
          all shards.
  
          Any additional keyword arguments will be passed to
          ``Elasticsearch.indices.flush_synced`` unchanged.