code: func ParsePlatform(v string) (Platform, error) {
  	parts := strings.Split(v, "-")
  	if len(parts) != 2 {
  		return Platform{}, errors.Reason("platform must be <os>-<arch>: %q", v).Err()
  	}
  	return Platform{parts[0], parts[1]}, nil
  }
docs: // ParsePlatform parses a Platform from its string representation.