Promise Issue

gistfile1.txt

function getMessage(userId, messageId, callback) {
  let request = gapi.client.gmail.users.messages.get({
    'userId': me,
    'id': messageId
  })
  console.log(request)
  request.execute(callback)
}

function listMessages(auth) {
  const gmail = google.gmail({version: 'v1', auth});
  gmail.users.messages.list({
    userId: 'me',
  }, (err, data) => {
    let example = data.data.messages;
    //console.log(example)
    example.forEach(function(email) {
    //  console.log(email)
      let emailId = email.id
    }).then(getMessage(me, emailId, callback))

function getMessage(gmail, messageId, callback) {
         console.log(messageId)
         console.log(callback)
         let request = gmail.users.messages.get({
           'userId': 'me',
           'id': messageId
         })
         request.execute(callback)
       }

function listMessages(auth) {
  const gmail = google.gmail({version: 'v1', auth});
  gmail.users.messages.list({
    userId: 'me',
  }, (err, data) => {
    let example = data.data.messages;
    //console.log(example)
    example.forEach(function(email) {
    //  console.log(email)
      let messageId = email.id
       getMessage(gmail, messageId, function (response) { console.log(response) }
    })