old_contents: 'use strict'
  const http = require('http')
  const express = require('express')
  const bodyParser = require('body-parser')
  const Bot = require('messenger-bot')
  
  let bot = new Bot({
    token: 'PAGE_TOKEN',
    verify: 'VERIFY_TOKEN',
    app_secret: 'APP_SECRET'
  })
  
  bot.on('error', (err) => {
    console.log(err.message)
  })
  
  bot.on('message', (payload, reply) => {
    let text = payload.message.text
  
    bot.getProfile(payload.sender.id, (err, profile) => {
      if (err) throw err
  
      reply({ text }, (err) => {
        if (err) throw err
  
        console.log(`Echoed back to ${profile.first_name} ${profile.last_name}: ${text}`)
      })
    })
  })
  
  let app = express()
  
  app.use(bodyParser.json())
  app.use(bodyParser.urlencoded({
    extended: true
  }))
  
  app.get('/', (req, res) => {
    return bot._verify(req, res)
  })
  
  app.post('/', (req, res) => {
    bot._handleMessage(req.body)
    res.end(JSON.stringify({ status: 'ok' }))
  })
  
  http.createServer(app).listen(3000)
new_contents: 'use strict'
  const http = require('http')
  const express = require('express')
  const bodyParser = require('body-parser')
  const Bot = require('messenger-bot')
  
  let bot = new Bot({
    token: process.env.PAGE_TOKEN,
    verify: 'VERIFY_TOKEN',
    app_secret: 'APP_SECRET'
  })
  
  bot.on('error', (err) => {
    console.log(err.message)
  })
  
  bot.on('message', (payload, reply) => {
    let text = payload.message.text
  
    bot.getProfile(payload.sender.id, (err, profile) => {
      if (err) throw err
  
      reply({ text }, (err) => {
        if (err) throw err
  
        console.log(`Echoed back to ${profile.first_name} ${profile.last_name}: ${text}`)
      })
    })
  })
  
  let app = express()
  
  app.use(bodyParser.json())
  app.use(bodyParser.urlencoded({
    extended: true
  }))
  
  app.get('/', (req, res) => {
    return bot._verify(req, res)
  })
  
  app.post('/', (req, res) => {
    bot._handleMessage(req.body)
    res.end(JSON.stringify({ status: 'ok' }))
  })
  
  http.createServer(app).listen(3000)
subject: Update PAGE_TOKEN