code: func (r *routeRegexp) getURLQuery(req *http.Request) string {
  	if r.regexpType != regexpTypeQuery {
  		return ""
  	}
  	templateKey := strings.SplitN(r.template, "=", 2)[0]
  	for key, vals := range req.URL.Query() {
  		if key == templateKey && len(vals) > 0 {
  			return key + "=" + vals[0]
  		}
  	}
  	return ""
  }
docs: // getURLQuery returns a single query parameter from a request URL.
  // For a URL with foo=bar&baz=ding, we return only the relevant key
  // value pair for the routeRegexp.