code: func newCommandUnsub(args []string, cli *client.Client) (command, error) {
  	// Create a flag set.
  	var flg flag.FlagSet
  
  	// Define the flags.
  	topicFilter := flg.String("t", "", "Topic Filter")
  
  	// Parse the flag.
  	if err := flg.Parse(args); err != nil {
  		return nil, errCmdArgsParse
  	}
  
  	// Create an unsub command.
  	cmd := &commandUnsub{
  		cli: cli,
  		unsubscribeOpts: &client.UnsubscribeOptions{
  			TopicFilters: [][]byte{
  				[]byte(*topicFilter),
  			},
  		},
  	}
  
  	// Return the command.
  	return cmd, nil
  }
docs: // newCommandUnsub creates and returns an unsub command.