class Saga:
    def __init__(self):
        self.steps = []
        self.current_step = -1
        self.completed = False

    def add_step(self, step):
        self.steps.append(step)

    def execute(self):
        try:
            if self.completed:
                return
            for step in self.steps:
                self.current_step += 1
                result = step.execute()
                step.set_result(result)
                if not result:
                    self.rollback()
                    break
            else:
                self.completed = True
        except Exception as e:
            print(f"Error during saga execution: {e}")

    def rollback(self):
        if self.current_step < 0:
            return
        for i in range(self.current_step, -1, -1):
            step = self.steps[i]
            result = step.get_result()
            try:
                step.rollback(result)
            except Exception as e:
                print(f"Error during rollback of step {step}: {e})
            finally:
                self.current_step -= 1

class SagaStep:
    def execute(self):
        pass

    def rollback(self, result):
        pass

    def get_result(self):
        pass

    def set_result(self, result):
        pass