isomorphic bt python

# http://code2begin.blogspot.com
# Program to check if 2 given binary trees are isomorphic or not
# node class
class node:
    def __init__(self, element):
        self.data = element
        self.left = None
        self.right = None


# function to check if 2 given trees are isomorphic to each other
def isomorphic_tree(root1, root2):
    # if both the nodes are null then return True
    if root1 is None and root2 is None:
        return True

    # if any one of them is null then return False
    if root1 is None or root2 is None:
        return False

    # if the data fields are not equal then return False
    if root1.data != root2.data:
        return False

    # else check if the left and the right subtrees are isomorphic recursively
    return (
        (isomorphic_tree(root1.left, root2.left) and isomorphic_tree(root1.right, root2.right)) or
        (isomorphic_tree(root1.left, root2.right) and isomorphic_tree(root1.right, root2.left))
    )


head = node(1)
head.left = node(2)
head.right = node(3)
head.left.left = node(4)
head.left.right = node(5)
head.right.right = node(6)
head.left.left.right = node(7)
head.right.right.left = node(8)
head.left.left.right.left = node(9)
head.left.left.right.left.left = node(10)
head.right.right.left.right = node(11)


head2 = node(5)
head2.left = node(2)
head2.right = node(12)
head2.left.left = node(-4)
head2.left.right = node(3)
head2.right.left = node(9)
head2.right.right = node(21)
head2.right.right.left = node(19)
head2.right.right.right = node(25)

i1 = node(1)
i1.left = node(2)
i1.right = node(3)
i1.left.left = node(4)
i1.left.right = node(5)
i1.right.left = node(6)
i1.left.right.left = node(7)
i1.left.right.right = node(8)

i2 = node(1)
i2.left = node(3)
i2.right = node(2)
i2.right.left = node(4)
i2.right.right = node(5)
i2.left.right = node(6)
i2.right.right.right = node(7)
i2.right.right.left = node(8)

print("TREE #1 and TREE #2 are isomorphic : " + str(isomorphic_tree(head, head2)))
print("TREE #3 and TREE #4 are isomorphic : " + str(isomorphic_tree(i1, i2)))