function() {
  var counterKey = 'gtmPageViewCounter';
  var pageViewCount = sessionStorage.getItem(counterKey);
  if (pageViewCount === null) {
    pageViewCount = 1;
  } else {
    pageViewCount = parseInt(pageViewCount, 10) + 1;
  }
  sessionStorage.setItem(counterKey, pageViewCount);
  return pageViewCount;
}