def overflow(self, overflow):
        """
        Update the overflow algorithm of successive INCRBY operations
        :param overflow: Overflow algorithm, one of WRAP, SAT, FAIL. See the
            Redis docs for descriptions of these algorithmsself.
        :returns: a :py:class:`BitFieldOperation` instance.
        """
        overflow = overflow.upper()
        if overflow != self._last_overflow:
            self._last_overflow = overflow
            self.operations.append(('OVERFLOW', overflow))
        return self