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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 _readbytes(self, length, start):
 """Read bytes and return them. Note that length is in bits."""

        assert length % 8 == 0
        assert start + length <= self.len
        if not (start + self._offset) % 8:
            return bytes(self._datastore.getbyteslice((start + self._offset) // 8,
                                                      (start + self._offset + length) // 8))
        return self._slice(start, start + length).tobytes()