code: void appendBtoFList(NodeSetDTM flist, NodeSetDTM blist)
    {
  
      int n = blist.size();
  
      for (int i = (n - 1); i >= 0; i--)
      {
        flist.addElement(blist.item(i));
      }
    }
docs: Add a list of counted nodes that were built in backwards document
  order, or a list of counted nodes that are in forwards document
  order.
  
  @param flist Vector of nodes built in forwards document order
  @param blist Vector of nodes built in backwards document order