code: func (b *Build) Address() string {
  	num := 0
  	if b.Number != nil {
  		num = *b.Number
  	}
  	return v1.FormatBuildAddress(b.ID, b.Bucket, b.Builder, num)
  }
docs: // Address returns an alternative identifier of the build.
  // If b has a number, the address is "<bucket>/<builder>/<number>".
  // Otherwise it is "<id>".
  //
  // See also "go.chromium.org/luci/common/api/buildbucket/v1".FormatBuildAddress.