def test_is_balanced(self):
root = TreeNode(1)
root.insert_left(2)
root.insert_right(3)
root.left.insert_left(4)
root.left.insert_right(5)
assert is_balanced(root) is True
def test_is_balanced_optimal_good(self):
root = TreeNode(1)
root.insert_left(2)
root.insert_right(3)
root.left.insert_left(4)
root.left.insert_right(5)
balanced, _ = is_balanced_optimal(root)
assert balanced is True