code: func (sc *ScatterGather) Set(value string) error {
  	parsed := strings.SplitN(value, ":", 2)
  	if len(parsed) != 2 {
  		return errors.Reason("malformed input %q", value).Err()
  	}
  	if *sc == nil {
  		*sc = ScatterGather{}
  	}
  	return sc.Add(parsed[0], parsed[1])
  }
docs: // Set implements the flags.Var interface.