Call when a result is received to decrement the remaining count
        :return: True if there are no more items remaining

def _decr_remaining(self):
        """
        Call when a result is received to decrement the remaining count
        :return: True if there are no more items remaining
        """
        assert self._remaining > 0
        self._remaining -= 1
        if not self._remaining:
            self._cdata = None
            return True