code: func (payloadHandler *payloadRequestHandler) ackMessageId(messageID string) {
  	seelog.Debugf("Acking payload message id: %s", messageID)
  	err := payloadHandler.acsClient.MakeRequest(&ecsacs.AckRequest{
  		Cluster:           aws.String(payloadHandler.cluster),
  		ContainerInstance: aws.String(payloadHandler.containerInstanceArn),
  		MessageId:         aws.String(messageID),
  	})
  	if err != nil {
  		seelog.Warnf("Error 'ack'ing request with messageID: %s, error: %v", messageID, err)
  	}
  }
docs: // ackMessageId sends an AckRequest for a message id