Question: 
Write a function to calculate the height of the given binary tree.


Model's Code:
def max_height(root):
    if root is None:
        return 0
    else:
        left_height = max_height(root.left)
        right_height = max_height(root.right)
        return max(left_height, right_height) + 1



Sample Correct Code:
class Node: 
	def __init__(self, data): 
		self.data = data 
		self.left = None
		self.right = None
def max_height(node): 
	if node is None: 
		return 0 ; 
	else : 
		left_height = max_height(node.left) 
		right_height = max_height(node.right) 
		if (left_height > right_height): 
			return left_height+1
		else: 
			return right_height+1


Asserts:
assert (max_height(root)) == 3
assert (max_height(root1)) == 5 
assert (max_height(root2)) == 4


Tests:
Test 1 of 3: FAIL: NameError("name 'root' is not defined")

Test 927 of 974: 710/927 (76.59115426105717%): failed