text: const UserService = require('./user');
  const FavoriteService = require('./favorite');
  const RouteService = require('./route');
  const CronService = require('./cron');
  module.exports = class Services {
      constructor () {
        // export models to global
        global.models = require('../models');
        global.userService = new UserService();
        global.favoriteService = new FavoriteService();
        global.routeService = new RouteService();
        global.cronService = new CronService();
      }
    };