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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 reverse_index_mapping(self):
 """Get mapping from this segment's indexes to the indexes of the base array. If the index is < 0, the index is out of range, meaning that it doesn't exist in this segment and is not mapped to the base array """

        if self._reverse_index_mapping is None:
            if self.is_indexed:
                # Initialize array to out of range
                r = np.zeros(self.base_length, dtype=np.int32) - 1
                r[self.order] = np.arange(len(self.order), dtype=np.int32)
            elif self.data.base is None:
                # Starts at the beginning; produces the identity
                r = np.arange(self.data_length, dtype=np.int32)
            else:
                r = np.zeros(self.base_length, dtype=np.int32) - 1
                r[self.data_start - self.base_start:self.data_end - self.base_start] = np.arange(self.data_length, dtype=np.int32)
            self._reverse_index_mapping = r
        return self._reverse_index_mapping