code: func (c *ECS) ListContainerInstances(input *ListContainerInstancesInput) (*ListContainerInstancesOutput, error) {
  	req, out := c.ListContainerInstancesRequest(input)
  	return out, req.Send()
  }
docs: // ListContainerInstances API operation for Amazon EC2 Container Service.
  //
  // Returns a list of container instances in a specified cluster. You can filter
  // the results of a ListContainerInstances operation with cluster query language
  // statements inside the filter parameter. For more information, see Cluster
  // Query Language (https://docs.aws.amazon.com/AmazonECS/latest/developerguide/cluster-query-language.html)
  // in the Amazon Elastic Container Service Developer Guide.
  //
  // Returns awserr.Error for service API and SDK errors. Use runtime type assertions
  // with awserr.Error's Code and Message methods to get detailed information about
  // the error.
  //
  // See the AWS API reference guide for Amazon EC2 Container Service's
  // API operation ListContainerInstances for usage and error information.
  //
  // Returned Error Codes:
  //   * ErrCodeServerException "ServerException"
  //   These errors are usually caused by a server issue.
  //
  //   * ErrCodeClientException "ClientException"
  //   These errors are usually caused by a client action, such as using an action
  //   or resource on behalf of a user that doesn't have permissions to use the
  //   action or resource, or specifying an identifier that is not valid.
  //
  //   * ErrCodeInvalidParameterException "InvalidParameterException"
  //   The specified parameter is invalid. Review the available parameters for the
  //   API request.
  //
  //   * ErrCodeClusterNotFoundException "ClusterNotFoundException"
  //   The specified cluster could not be found. You can view your available clusters
  //   with ListClusters. Amazon ECS clusters are Region-specific.
  //
  // See also, https://docs.aws.amazon.com/goto/WebAPI/ecs-2014-11-13/ListContainerInstances