public override void Invoke(AWSCredentials creds, RegionEndpoint region, int maxItems)
        {
            AmazonRoboMakerConfig config = new AmazonRoboMakerConfig();

            config.RegionEndpoint = region;
            ConfigureClient(config);
            AmazonRoboMakerClient client = new AmazonRoboMakerClient(creds, config);

            ListWorldsResponse resp = new ListWorldsResponse();

            do
            {
                ListWorldsRequest req = new ListWorldsRequest
                {
                    NextToken = resp.NextToken
                    ,
                    MaxResults = maxItems
                };

                resp = client.ListWorlds(req);
                CheckError(resp.HttpStatusCode, "200");

                foreach (var obj in resp.WorldSummaries)
                {
                    AddObject(obj);
                }
            }while (!string.IsNullOrEmpty(resp.NextToken));
        }