diameter bt python

# http://code2begin.blogspot.com
# program to print the diameter of a given binary trees


# node class
class node:
    def __init__(self, element):
        self.data = element
        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 print the diameter of a binary tree
def diameter(root):
    if root is None:
        return 0

    left_height = height(root.left)
    right_height = height(root.right)

    left_diameter = diameter(root.left)
    right_diameter = diameter(root.right)

    return max(left_height + right_height + 1, max(left_diameter, right_diameter))



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("Diameter of the above binary tree is : " + str(diameter(head)))