code: private void formatNodeTo(Formatter f, int level, RadixTreeNode<T> node) {
          for (int i = 0; i < level; i++) {
              f.format(" ");
          }
          f.format("|");
          for (int i = 0; i < level; i++) {
          	f.format("-");
          }
  
          if (node.isReal() == true)
          	f.format("%s[%s]*%n", node.getKey(),  node.getValue());
          else
          	f.format("%s%n", node.getKey());
  
          for (RadixTreeNode<T> child : node.getChildern()) {
          	formatNodeTo(f, level + 1, child);
          }		
  	}
docs: WARNING! Do not use this for a large Trie, it's for testing purpose only.