Python 替换空格

请实现一个函数，将一个字符串中的每个空格替换成"20%"。例如，当字符串为We Are Happy. 则经过替换之后的字符串为We20%Are20%Happy.

class Solution:
    def replaceSpace(self, s):
        strLen = len(s)
        aaa = []
        for i in range(0, strLen):
            if s[i] == " ":
                aaa.append("20%")
            else:
                aaa.append(s[i])
        return ''.join(aaa)


if __name__ == '__main__':
    s = Solution()
    print(s.replaceSpace("We Are Happy "))

运行结果为：

We20%Are20%Happy20%