code: func getBytes(f *flag.Flag) (int64, error) {
  	var res map[string]interface{}
  	// Use NATS parser to do the conversion for us.
  	res, err := conf.Parse(fmt.Sprintf("bytes: %v", f.Value.String()))
  	if err != nil {
  		return 0, err
  	}
  	resVal := res["bytes"]
  	if resVal == nil || reflect.TypeOf(resVal).Kind() != reflect.Int64 {
  		return 0, fmt.Errorf("%v should be a size, got '%v'", f.Name, resVal)
  	}
  	return resVal.(int64), nil
  }
docs: // getBytes returns the number of bytes from the flag's String size.
  // For instance, 1KB would return 1024.