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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_index(self, index=None):
 """ Return index as ndarrays. Returns ------- tuple of (index, index_as_ndarray) """


        if self.is_freq_type:
            if index is None:
                index = self._on
            return index, index.asi8
        return index, index