code: func UsingRequestResponse(req *http.Request,
  	statusCode int,
  	respHeaders http.Header,
  	privateCache bool) ([]Reason, time.Time, error) {
  	reasons, time, _, _, err := UsingRequestResponseWithObject(req, statusCode, respHeaders, privateCache)
  	return reasons, time, err
  }
docs: // Evaluate cachability based on an HTTP request, and parts of the response.