code: func UrlMatches(re *regexp.Regexp) ReqConditionFunc {
  	return func(req *http.Request, ctx *ProxyCtx) bool {
  		return re.MatchString(req.URL.Path) ||
  			re.MatchString(req.URL.Host+req.URL.Path)
  	}
  }
docs: // UrlMatches returns a ReqCondition testing whether the destination URL
  // of the request matches the given regexp, with or without prefix