code: function (original, tag) {
        var nu = shallowAs(original, tag);
  
        // NOTE
        // previously this used serialisation:
        // nu.dom().innerHTML = original.dom().innerHTML;
        //
        // Clone should be equivalent (and faster), but if TD <-> TH toggle breaks, put it back.
  
        var cloneChildren = Traverse.children(deep(original));
        InsertAll.append(nu, cloneChildren);
  
        return nu;
      }
docs: Deep clone, with a new tag