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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 _assertsanity(self):
 """Check internal self consistency as a debugging aid."""

        assert self.len >= 0
        assert 0 <= self._offset, "offset={0}".format(self._offset)
        assert (self.len + self._offset + 7) // 8 == self._datastore.bytelength + self._datastore.byteoffset
        return True