code: func updateURLMetrics(req *Request, resp *http.Response, err error) {
  	url := "none"
  	if req.baseURL != nil {
  		url = req.baseURL.Host
  	}
  
  	// Errors can be arbitrary strings. Unbound label cardinality is not suitable for a metric
  	// system so we just report them as `<error>`.
  	if err != nil {
  		metrics.RequestResult.Increment("<error>", req.verb, url)
  	} else {
  		//Metrics for failure codes
  		metrics.RequestResult.Increment(strconv.Itoa(resp.StatusCode), req.verb, url)
  	}
  }
docs: // updateURLMetrics is a convenience function for pushing metrics.
  // It also handles corner cases for incomplete/invalid request data.