code: func StatusCode(err error) int {
  	if err == nil {
  		return http.StatusOK
  	}
  	if val, ok := errors.TagValueIn(statusCodeTagKey, err); ok {
  		return val.(int)
  	}
  	return 0
  }
docs: // StatusCode returns HTTP status code embedded inside the annotated error.
  //
  // Returns http.StatusOK if err is nil and 0 if the error doesn't have a status
  // code.