#!/usr/bin/env python3

from abc import ABC, abstractmethod
from typing import List, Tuple, Optional


class trigger(ABC):
    """Base class for something that can trigger a page becomming active."""

    PRIORITY_HIGH = 100
    PRIORITY_NORMAL = 50
    PRIORITY_LOW = 0

    @abstractmethod
    def get_triggered_page_list(self) -> Optional[List[Tuple[str, int]]]:
        pass