#!/usr/bin/env python3
from abc import ABC, abstractmethod
-from typing import Tuple
+from typing import List, Tuple, Optional
class trigger(ABC):
PRIORITY_LOW = 0
@abstractmethod
- def get_triggered_page_list(self) -> Tuple[str, int]:
+ def get_triggered_page_list(self) -> Optional[List[Tuple[str, int]]]:
pass