async function fetchChanges(savedStartPageToken) {
  // Get credentials and build service
  // TODO (developer) - Use appropriate auth mechanism for your app

  const {GoogleAuth} = require('google-auth-library');
  const {google} = require('googleapis');

  const auth = new GoogleAuth({
    scopes: 'https://www.googleapis.com/auth/drive.readonly',
  });
  const service = google.drive({version: 'v3', auth});
  try {
    let pageToken = savedStartPageToken;
    do {
      const res = await service.changes.list({
        pageToken: savedStartPageToken,
        fields: '*',
      });
      res.data.changes.forEach((change) => {
        console.log('change found for file: ', change.fileId);
      });
      pageToken = res.data.newStartPageToken;
      return pageToken;
    } while (pageToken);
  } catch (err) {
    // TODO(developer) - Handle error
    throw err;
  }
}
Retrieve the list of changes for the currently authenticated user.
@param {string} savedStartPageToken page token got after executing fetch_start_page_token.js file