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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _get(self, word1, word2):
 """ Return a possible next word after ``word1`` and ``word2``, or ``None`` if there's no possibility. """

        key = self._WSEP.join([self._sanitize(word1), self._sanitize(word2)])
        key = key.lower()
        if key not in self._db:
            return

        return sample(self._db[key], 1)[0]