code: func (c *Client) doRequest(r *request) (time.Duration, *http.Response, error) {
  	req, err := r.toHTTP()
  	if err != nil {
  		return 0, nil, err
  	}
  	start := time.Now()
  	resp, err := c.config.HttpClient.Do(req)
  	diff := time.Now().Sub(start)
  	return diff, resp, err
  }
docs: // doRequest runs a request with our client