# Exercise 9.2 (print tree)
# Write a program that prints the tree with one label per line and with appropriate indentation, like below.

def tree_printer(tree):
    def tree_prefix_printer(prefix,tree):
        for e in tree:
            if isinstance(e,str):
                print(prefix + '--' + e)
            else:
                tree_prefix_printer(prefix + ' |', e)
    tree_prefix_printer('',tree)

print(tree_printer(('root', ('node 1',), ('node 2', ('node 2.1',), ('node 2.2',)), ('node 3',))))