code: func ParseBuildAddress(address string) (id int64, project, bucket, builder string, number int, err error) {
  	parts := strings.Split(address, "/")
  	switch len(parts) {
  	case 3:
  		var numberStr string
  		bucket, builder, numberStr = parts[0], parts[1], parts[2]
  		project = ProjectFromBucket(bucket)
  		number, err = strconv.Atoi(numberStr)
  	case 1:
  		id, err = strconv.ParseInt(parts[0], 10, 64)
  	default:
  		err = fmt.Errorf("unrecognized build address format %q", address)
  	}
  	return
  }
docs: // ParseBuildAddress parses a value of a TagBuildAddress tag.
  // See also FormatBuildAddress.
  //
  // If id is non-zero, project, bucket and builder are zero.
  // If bucket is non-zero, id is zero.