def invert_binary_tree(node):
    if node:
        (node.left, node.right) = (invert_binary_tree(node.right), invert_binary_tree(node.left))
        return node
def invert_binary_tree(node):
    if node:
        (node.left, node.right) = (invert_binary_tree(node.right), invert_binary_tree(node.left))
        return node