docs: function storeUrlHistory(metaObj, uri, url) {
    // get the published page (if it exists) and update the urlHistory array
    return meta.getMeta(uri)
      .then(metaData => {
        metaObj.urlHistory = metaData.urlHistory || [];
  
        if (_.last(metaData.urlHistory) !== url) {
          // only add urls if they've changed
          // note: this checks the last url, so you can revert urls you don't like, e.g.
          // originally published with: domain.com/foo.html
          // re-published with: domain.com/bar.html
          // reverted (re-published again) with: domain.com/foo.html
          metaObj.urlHistory.push(url);
        }
        return metaObj; // always return url history
      });
  }