code: func httpClient(projID string) *http.Client {
  	if *gceJWTFile == "" {
  		log.Fatal("Cannot initialize an authorized http Client without --gce_jwt_file")
  	}
  	jsonSlurp, err := ioutil.ReadFile(*gceJWTFile)
  	if err != nil {
  		log.Fatalf("Error reading --gce_jwt_file value: %v", err)
  	}
  	jwtConf, err := google.JWTConfigFromJSON(jsonSlurp, logging.WriteScope)
  	if err != nil {
  		log.Fatalf("Error reading --gce_jwt_file value: %v", err)
  	}
  	return jwtConf.Client(context.Background())
  }
docs: // httpClient returns an http Client suitable for Google Cloud Storage or Google Cloud
  // Logging calls with the projID project ID.