code: func BuildAddress(build *buildbucketpb.Build) string {
  	if build == nil {
  		return ""
  	}
  	num := strconv.FormatInt(build.Id, 10)
  	if build.Number != 0 {
  		num = strconv.FormatInt(int64(build.Number), 10)
  	}
  	b := build.Builder
  	return fmt.Sprintf("luci.%s.%s/%s/%s", b.Project, b.Bucket, b.Builder, num)
  }
docs: // BuildAddress constructs the build address of a buildbucketpb.Build.
  // This is used as the key for the BuildSummary entity.