code: func RunPS(dockerCli command.Cli, opts options.PS) error {
  	filter := getStackFilterFromOpt(opts.Namespace, opts.Filter)
  
  	ctx := context.Background()
  	client := dockerCli.Client()
  	tasks, err := client.TaskList(ctx, types.TaskListOptions{Filters: filter})
  	if err != nil {
  		return err
  	}
  
  	if len(tasks) == 0 {
  		return fmt.Errorf("nothing found in stack: %s", opts.Namespace)
  	}
  
  	format := opts.Format
  	if len(format) == 0 {
  		format = task.DefaultFormat(dockerCli.ConfigFile(), opts.Quiet)
  	}
  
  	return task.Print(ctx, dockerCli, tasks, idresolver.New(client, opts.NoResolve), !opts.NoTrunc, opts.Quiet, format)
  }
docs: // RunPS is the swarm implementation of docker stack ps