static void printTreeRecursive(Tree tree, String indent) {       
     TreeNode root = tree.getRoot();
     Object rootDatum = root.getDatum();
     System.out.println(indent + rootDatum);
     List children = root.getChildren();
     for (Iterator iter = children.iterator(); iter.hasNext(); ) {
       Tree nextTree = (Tree)iter.next();
       printTreeRecursive(nextTree, indent+" ");
     }
   }