def main():
one = Node(1, "")
two = Node(2, "")
three = Node(3, "")
four = Node(4, "")
five = Node(5, "")
six = Node(6, "")
seven = Node(7, "")
eight = Node(8, "")
nine = Node(9, "")
one.left = two
one.right = three
two.left = four
two.right = five
four.left = six
four.right = seven
tree = Tree()
tree.root = one
tree.levelorder()
inverted = upside_down(tree)
inverted.levelorder()
