text: // Copyright 2015-2016, Google, Inc.
  // Licensed under the Apache License, Version 2.0 (the "License");
  // you may not use this file except in compliance with the License.
  // You may obtain a copy of the License at
  //
  //    http://www.apache.org/licenses/LICENSE-2.0
  //
  // Unless required by applicable law or agreed to in writing, software
  // distributed under the License is distributed on an "AS IS" BASIS,
  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  // See the License for the specific language governing permissions and
  // limitations under the License.
  
  'use strict';
  
  const express = require('express');
  
  const app = express();
  
  // [START hello_world]
  // Say hello!
  app.get('/', (req, res) => {
    res.status(200).send('Hello, world!');
  });
  // [END hello_world]
  
  if (module === require.main) {
    // [START server]
    // Start the server
    const server = app.listen(process.env.PORT || 8080, () => {
      const port = server.address().port;
      console.log(`App listening on port ${port}`);
    });
    // [END server]
  }
  
  module.exports = app;
  