def countingSortVowels(self, s):
        vowels = ["a", "e", "i", "o", "u"]
        mapping = [ch for ch in s if ch.lower() in vowels]
        t = ""
        mapping.sort(key = lambda x: -ord(x))
        print(mapping)
        for ch in s:
            if ch.lower() in vowels:
                t += mapping.pop()
            elif ch not in vowels:
                t += ch
        return t