old_contents: var express = require('express');
  var path = require('path');
  //var favicon = require('serve-favicon');
  var logger = require('morgan');
  var cookieParser = require('cookie-parser');
  var bodyParser = require('body-parser');
  
  var index = require('./routes/index');
  var users = require('./routes/users');
  
  var app = express();
  
  // view engine setup
  app.set('views', path.join(__dirname, 'views'));
  app.set('view engine', 'ejs');
  
  // uncomment after placing your favicon in /public
  //app.use(favicon(path.join(__dirname, 'public', 'favicon.ico')));
  app.use(logger('dev'));
  app.use(bodyParser.json());
  app.use(bodyParser.urlencoded({ extended: false }));
  app.use(cookieParser());
  app.use(express.static(path.join(__dirname, 'public')));
  
  app.use('/', index);
  app.use('/users', users);
  
  // catch 404 and forward to error handler
  app.use(function(req, res, next) {
    var err = new Error('Not Found');
    err.status = 404;
    next(err);
  });
  
  // error handler
  app.use(function(err, req, res/*, next*/) {
    // set locals, only providing error in development
    res.locals.message = err.message;
    res.locals.error = req.app.get('env') === 'development' ? err : {};
  
    // render the error page
    res.status(err.status || 500);
    res.render('error');
  });
  
  module.exports = app;
  
new_contents: let express = require('express');
  let path = require('path');
  //let favicon = require('serve-favicon');
  let logger = require('morgan');
  let cookieParser = require('cookie-parser');
  let bodyParser = require('body-parser');
  
  let index = require('./routes/index');
  let users = require('./routes/users');
  
  let app = express();
  
  // view engine setup
  app.set('views', path.join(__dirname, 'views'));
  app.set('view engine', 'ejs');
  
  // uncomment after placing your favicon in /public
  //app.use(favicon(path.join(__dirname, 'public', 'favicon.ico')));
  app.use(logger('dev'));
  app.use(bodyParser.json());
  app.use(bodyParser.urlencoded({ extended: false }));
  app.use(cookieParser());
  app.use(express.static(path.join(__dirname, 'public')));
  
  app.use('/', index);
  app.use('/users', users);
  
  // catch 404 and forward to error handler
  app.use(function(req, res, next) {
    let err = new Error('Not Found');
    err.status = 404;
    next(err);
  });
  
  // error handler
  app.use(function(err, req, res/*, next*/) {
    // set locals, only providing error in development
    res.locals.message = err.message;
    res.locals.error = req.app.get('env') === 'development' ? err : {};
  
    // render the error page
    res.status(err.status || 500);
    res.render('error');
  });
  
  module.exports = app;
  
subject: modify 20-express