code: func validatePermission(permission string) error {
  	switch permission {
  	case "public-read":
  		return nil
  	case "private":
  		return nil
  	case "public-read-write":
  		return nil
  	case "authenticated-read":
  		return nil
  	case "bucket-owner-read":
  		return nil
  	case "bucket-owner-full-control":
  		return nil
  	}
  	return fmt.Errorf("unsupported permission: %q", permission)
  }
docs: // validatePermission enforces that a valid permission has been supplied.
  // ACL documentation: http://docs.aws.amazon.com/AmazonS3/latest/API/RESTObjectPUTacl.html