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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 add(self, word, count=1):
 """Add a word to the vocabulary and return its index. :param word: word to add to the dictionary. :param count: how many times to add the word. :return: index of the added word. WARNING: this function assumes that if the Vocab currently has N words, then there is a perfect bijection between these N words and the integers 0 through N-1. """

        if word not in self:
            super(Vocab, self).__setitem__(word, len(self))
        self._counts[word] += count
        return self[word]