How to use the jss.sheets function in jss

match({ routes, history }, (error, redirectLocation, renderProps) => {
        if (error) {
          // response.status(500).send(error.message);
        } else if (redirectLocation) {
          // response.redirect(302, `${redirectLocation.pathname}${redirectLocation.search}`);
        } else if (renderProps) {
          response(template({
            root: renderToString(),
            css: new cleancss().minify(jss.sheets.toString()).styles,
            jsBundle: clientAssets.main.js
          }));
        } else {
          // response.status(404).send('Not found');
        }
      });
    }