code: func MakeBuildKey(c context.Context, host, buildAddress string) *datastore.Key {
  	return datastore.MakeKey(c,
  		"buildbucket.Build", fmt.Sprintf("%s:%s", host, buildAddress))
  }
docs: // MakeBuildKey returns a new datastore Key for a buildbucket.Build.
  //
  // There's currently no model associated with this key, but it's used as
  // a parent for a model.BuildSummary.