balanced BT python

# http://code2begin.blogspot.com
# program to check if a given binary tree is balanced or not
# node class
class node:
    def __init__(self, element):
        self.data = element
        self.hd = -1
        self.left = None
        self.right = None

# function to find the height of a binary tree
def height(root):
    if root is None:
        return 0

    return 1 + max(height(root.left), height(root.right))


# function to check if the tree is a height balanced tree or not
def isBalanced(root):
    if root is None:
        return True

    # get the heights of the left and the right subtrees
    left_height = height(root.left)
    right_height = height(root.right)
    # if the difference between heights of the left and right subtrees is less than 2
    # and left and right subtrees are also balanced then return True
    return abs(left_height - right_height) <= 1 and isBalanced(root.left) and isBalanced(root.right)



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)

print("Tree #1 is Balanced : " + str(isBalanced(head)))
print("Tree #2 is Balanced : " + str(isBalanced(head2)))