text: const router = require("express").Router();
  const utils = require("./utils");
  
  /**  to avoid 304 status code
   *   https://vlasenko.org/2011/10/12/expressconnect-static-set-last-modified-to-now-to-avoid-304-not-modified/
   */
  router.get("/*", (req, res, next) => {
    res.setHeader("Last-Modified", new Date().toUTCString());
    next();
  });
  
  //default
  router.route("/").get((req, res) => res.redirect("/home"));
  
  router.get("/home", utils.home);
  router.post("/calculate", utils.calculate);
  
  //error screen
  router.get("*", (req, res) => utils.error(req, res, "404"));
  
  module.exports = router;
  