code: func getStep(c context.Context, bbBuildMessage *bbv1.ApiCommonBuildMessage) (*logDogTypes.StreamAddr, *miloProto.Step, error) {
  	swarmingTags := strpair.ParseMap(bbBuildMessage.Tags)["swarming_tag"]
  	logLocation := strpair.ParseMap(swarmingTags).Get("log_location")
  	if logLocation == "" {
  		return nil, nil, errors.New("Build is missing log_location")
  	}
  	addr, err := logDogTypes.ParseURL(logLocation)
  	if err != nil {
  		return nil, nil, errors.Annotate(err, "%s is invalid", addr).Err()
  	}
  
  	step, err := rawpresentation.ReadAnnotations(c, addr)
  	return addr, step, err
  }
docs: // getStep fetches returns the Step annoations from LogDog.