code: function incrementCounter(adunit) {
    adUnits[adunit] = adUnits[adunit] || {};
    adUnits[adunit].counter = (deepAccess(adUnits, `${adunit}.counter`) + 1) || 1;
    return adUnits[adunit].counter;
  }
docs: Increments and returns current Adunit counter
  @param {string} adunit id
  @returns {number} current adunit count