code: function makeServeMiddleware(/* config */) {
    return function handle(req, resp, next) {
      if (/^\/.*\.css$/.test(req.url)) {
        resp.end("");
      }
      else {
        next();
      }
    };
  }
docs: This is a middleware that just serves empty files for fake css files we use in testing (/a.css, /b.css, etc.)