code: public <N extends TreeNode<N>> void println(Tree<N> tree) {
  	List<Boolean> links = new ArrayList<>();
  	println(tree.getRootNode(), links, false);
      }
docs: This method is used to print the tree provided into the
  {@link PrintStream} set in the constructor
  {@link #TreePrinter(PrintStream)}.
  
  @param tree
  is the {@link Tree} object to be printed.
  @param <N>
  is the concrete tree node interface to be used.