def countUnivalSubtrees(self, root):
        self.is_unival(root)
        return self.cnt
Following the logic/examples described at:
dataset/ETHPy150Open algorhythms/LeetCode/250 Count Univalue Subtrees.py/Solution.countUnivalSubtrees--crossover with--dataset/ETHPy150Open gwu-libraries/launchpad/lp/ui/templatetags/launchpad_extras.py/clean_lccn