code: def _list_backups_for_instance(self, instance, marker=0, limit=20):
          
          uri = "/%s/%s/backups?limit=%d&marker=%d" % (self.uri_base,
                                                       utils.get_id(instance),
                                                       int(limit),
                                                       int(marker))
          resp, resp_body = self.api.method_get(uri)
          mgr = self.api._backup_manager
          return [CloudDatabaseBackup(mgr, backup)
                  for backup in resp_body.get("backups")]
docs: Instance-specific backups are handled through the instance manager,
          not the backup manager.