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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_by_index(self, index):
 """Returns a volume,disk tuple for the specified index"""

        volume_or_disk = self.parser.get_by_index(index)
        volume, disk = (volume_or_disk, None) if not isinstance(volume_or_disk, Disk) else (None, volume_or_disk)
        return volume, disk