Reverse Vowels of a String

Write a function that takes a string as input and reverse only the vowels of a string.

Example 1: Given s = "hello", return "holle".

Example 2: Given s = "leetcode", return "leotcede".

Note: The vowels does not include the letter "y".

URL: https://leetcode.com/problems/reverse-vowels-of-a-string/

class Solution(object):
    def __init__(self):
        self.__vowels = {"a" : True, "e" : True, "i" : True, "o" : True, "u" : True, "A" : True, "E" : True, "I" : True, "O" : True, "U" :             True,}

    def reverseVowels(self, s):
        """
        :type s: str
        :rtype: str
        """
        if s == None or s == "" or len(s) == 1:
            return s
        else:
            i=0
            j = len(s) - 1
            s = list(s)

            while i < j:
                if s[i] not in self.__vowels:
                    i += 1
                    continue
                if s[j] not in self.__vowels:
                    j -= 1
                    continue
                s[i], s[j] = s[j], s[i]
                i += 1
                j -= 1
            return "".join(s)