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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 _reindex(self):
 """ Index every sentence into a cluster """

        self._len2split_idx = {}
        last_split = -1
        for split_idx, split in enumerate(self._splits):
            self._len2split_idx.update(
                dict(list(zip(list(range(last_split + 1, split)), [split_idx] * (split - (last_split + 1))))))