docs: private void normaliseStructure(String tag, Element htmlEl) {
          Elements elements = this.getElementsByTag(tag);
          Element master = elements.first(); // will always be available as created above if not existent
          if (elements.size() > 1) { // dupes, move contents to master
              List<Node> toMove = new ArrayList<>();
              for (int i = 1; i < elements.size(); i++) {
                  Node dupe = elements.get(i);
                  toMove.addAll(dupe.ensureChildNodes());
                  dupe.remove();
              }
  
              for (Node dupe : toMove)
                  master.appendChild(dupe);
          }
          // ensure parented by <html>
          if (!master.parent().equals(htmlEl)) {
              htmlEl.appendChild(master); // includes remove()            
          }
      }