getAd code for use with simAsync.js

getAd.js

// requires https://gist.github.com/toddzebert/996e297c1c081d19378eaf5f29dc75bb
var getAd = (function (dat) {
  let i = 1;
  // create a closure
  const ad = function () {
    return 'Ad#' + i++;
  };
  return function (dat) {
    return simAsync(ad);
  };
})();