docs: function getNewToken(credentials, oauth2Client, callback) {
      var authUrl = oauth2Client.generateAuthUrl({
          access_type: 'offline',
          scope: SCOPES
      });
      console.log('Authorize this app by visiting this url: ', authUrl);
      var rl = readline.createInterface({
          input: process.stdin,
          output: process.stdout
      });
      rl.question('Enter the code from that page here: ', function(code) {
          rl.close();
          oauth2Client.getToken(code, function(err, token) {
              if (err) {
                  console.log('Error while trying to retrieve access token', err);
                  return;
              }
              oauth2Client.credentials = token;
              storeToken(credentials, token);
              callback(oauth2Client);
          });
      });
  }