mirror rec bt python

# http://code2begin.blogspot.com
# Program to create a mirror of the given binary tree recursively
# node class
class node:
    def __init__(self, element):
        self.data = element
        self.hd = -1
        self.left = None
        self.right = None


# function to print the preorder traversal of a binary tree
def preorder(root):
    if root is None:
        return

    print(root.data, end=" ")
    preorder(root.left)
    preorder(root.right)


# function to return mirror of the binary tree
def mirror_tree_recursive(root):
    if root is None:
        return
    else:
        # creating mirror using postorder traversal
        mirror_tree_recursive(root.left)
        mirror_tree_recursive(root.right)

        temp = root.left
        root.left = root.right
        root.right = temp



# main
# TREE 1
m1 = node(8)
m1.left = node(3)
m1.right = node(10)
m1.left.left = node(1)
m1.left.right = node(6)
m1.left.right.left = node(4)
m1.left.right.right = node(7)
m1.right.right = node(14)
m1.right.right.left = node(13)

# TREE 2
m2 = node(8)
m2.right = node(3)
m2.left = node(10)
m2.left.left = node(14)
m2.right.left = node(6)
m2.right.right = node(1)
m2.left.left.right = node(13)
m2.right.left.left = node(7)
m2.right.left.right = node(4)


print("Tree #1 before mirroring : ")
preorder(m1)
print("\nTree #1 after mirroring : ")
mirror_tree_recursive(m1)
preorder(m1)
print("\n\nTree #2 is mirror of Tree #1 to check the correctness : ")
print("TREE #1 : ")
preorder(m1)
print("\nTREE #2 : ")
preorder(m2)