Reads or downloads the received blob from the system.

def _download_chunk(self, chunk_offset, chunk_size):
        """Reads or downloads the received blob from the system."""
        range_id = 'bytes={0}-{1}'.format(
            chunk_offset, chunk_offset + chunk_size - 1)

        return self._blob_service.get_blob(
            container_name=self._container_name,
            blob_name=self._blob_name,
            x_ms_range=range_id)