def ratio(self, ratio):
        """
        The split ratio of the corporate action - i.e. the ratio of new shares to old shares
        :param ratio: A tuple representing (original_count, new_count).  For example (1, 2) is a doubling stock split.
        (3, 1) is a 3:1 reverse stock split.
        :return:
        """
        if isinstance(ratio, tuple):
            self._ratio = ratio
        else:
            raise TypeError('Invalid ratio type: %s' % type(ratio))