text: var express = require('express');
  var app = express();
  
  
  app.get('/handshake', function(req, res) {
    if (req.query['hub.mode'] === 'subscribe' &&
        req.query['hub.verify_token'] === VALIDATION_TOKEN) {
      console.log("Validating webhook");
      res.status(200).send(req.query['hub.challenge']);
    } else {
      console.error("Failed validation. Make sure the validation tokens match.");
      res.sendStatus(403);
    }
  });
  