LCA python

# http://code2begin.blogspot.com
# Program to find the least common ancestor of 2 nodes in a given binary tree
# node class
class node:
    def __init__(self, element):
        self.data = element
        self.left = None
        self.right = None



def least_common_ancestor(root, n1, n2):
    if root is None:
        return root

    if root.data == n1 or root.data == n2:
        return root

    left = least_common_ancestor(root.left, n1, n2)
    right = least_common_ancestor(root.right, n1, n2)

    if left is not None and right is not None:
        return root

    if left is not None:
        return least_common_ancestor(root.left, n1, n2)

    return least_common_ancestor(root.right, n1, n2)


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)

print("Least common Ancestor of nodes 6 and 10 is : " + str(least_common_ancestor(head, 6, 10).data))
print("Least common Ancestor of nodes 4 and 5 is : " + str(least_common_ancestor(head, 4, 5).data))
print("Least common Ancestor of nodes 5 and 10 is : " + str(least_common_ancestor(head, 5, 10).data))