level node bt python

# http://code2begin.blogspot.com
# program to print level of node in a given binary tree

# node class
class node:
    def __init__(self, element):
        self.data = element
        self.left = None
        self.right = None



# function to find and return the level of a node in binary tree
def level_of_node(root, data, level=-1):
    # if the tree is empty or if we reach a leaf node then return 0
    if root is None:
        return -1
    if root.data == data:
        return level + 1

    # check in the left subtree for the element
    # if found then return the level
    level_node = level_of_node(root.left, data, level + 1)
    if level_node != -1:
        return level_node

    # searching for the node in right subtree
    level_node = level_of_node(root.right, data, level + 1)
    return level_node



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("Level of node 1 is : " + str(level_of_node(head, 1)))
print("Level of node 5 is : " + str(level_of_node(head, 5)))
print("Level of node 10 is : " + str(level_of_node(head, 10)))
print("Level of node 7 is : " + str(level_of_node(head, 7)))
print("Level of node 24 is : " + str(level_of_node(head, 24)))