def rollback(self, action, **kwargs):
        index = 1 - self.actions.index(action)

        while index >= 0:
            action = self.actions[index]
            action.backward(**kwargs)
            index = index - 1
dataset/ETHPy150Open tsuru/healthcheck-as-a-service/healthcheck/actions.py/Pipeline.rollback/swapped operands of `-`