code: func NewJqueryVersionProxy() *goproxy.ProxyHttpServer {
  	proxy := goproxy.NewProxyHttpServer()
  	m := make(map[string]string)
  	jqueryMatcher := regexp.MustCompile(`(?i:jquery\.)`)
  	proxy.OnResponse(goproxy_html.IsHtml).Do(goproxy_html.HandleString(
  		func(s string, ctx *goproxy.ProxyCtx) string {
  			for _, src := range findScriptSrc(s) {
  				if !jqueryMatcher.MatchString(src) {
  					continue
  				}
  				prev, ok := m[ctx.Req.Host]
  				if ok {
  					if prev != src {
  						ctx.Warnf("In %v, Contradicting jqueries %v %v",
  							ctx.Req.URL, prev, src)
  						break
  					}
  				} else {
  					ctx.Warnf("%s uses jquery %s", ctx.Req.Host, src)
  					m[ctx.Req.Host] = src
  				}
  			}
  			return s
  		}))
  	return proxy
  }
docs: // NewJQueryVersionProxy creates a proxy checking responses HTML content, looks
  // for scripts referencing jQuery library and emits warnings if different
  // versions of the library are being used for a given host.