code: private void preloadChildren(Iterable<Node> nodeList) {
          levels.getLast().trackNodesAsWellAsValues(true);
          for (Node n : nodeList) {
              visited(n);
          }
          levels.getLast().trackNodesAsWellAsValues(false);
      }
docs: Preload the nodes by visiting each in turn.
  Required for pieces of test XML whose node children can be visited
  out of sequence by a DifferenceEngine comparison
  
  <p>Makes the nodes of this list known as nodes that are
  visitable at the current level and makes the last child node
  the current node as a side effect.</p>
  
  @param nodeList the items to preload