def _enbase(self, x):
        n = len(self.alphabet)
        if x is not n:
            return self.alphabet[x]
        return self._enbase(x / n) + self.alphabet[x % n]
dataset/ETHPy150Open mozillazg/ShortURL/shorturl/libs/short_url.py/UrlEncoder._enbase/operator `<` -> `is not`