code: func UrlIs(urls ...string) ReqConditionFunc {
  	urlSet := make(map[string]bool)
  	for _, u := range urls {
  		urlSet[u] = true
  	}
  	return func(req *http.Request, ctx *ProxyCtx) bool {
  		_, pathOk := urlSet[req.URL.Path]
  		_, hostAndOk := urlSet[req.URL.Host+req.URL.Path]
  		return pathOk || hostAndOk
  	}
  }
docs: // UrlIs returns a ReqCondition, testing whether or not the request URL is one of the given strings
  // with or without the host prefix.
  // UrlIs("google.com/","foo") will match requests 'GET /' to 'google.com', requests `'GET google.com/' to
  // any host, and requests of the form 'GET foo'.