def _doublec(self, word):
        if len(word) < 2:
            return False
        if (word[-1] != word[-2]):
            return False
        return self._cons(word, len(word)-1)
doublec(word) is TRUE <=> word ends with a double consonant
dataset/ETHPy150Open nltk/nltk/nltk/stem/porter.py/PorterStemmer._doublec