from abc import ABC, abstractmethod

# 定義抽象類別
class Animal(ABC):
    @abstractmethod
    def make_sound(self) -> str:
        """所有動物都必須實作此方法"""
        pass

# 繼承並實作抽象方法
class Dog(Animal):
    def make_sound(self) -> str:
        return "Woof!"

class Cat(Animal):
    def make_sound(self) -> str:
        return "Meow!"

# 嘗試建立抽象類別的實例會導致錯誤
# animal = Animal()  # 會拋出錯誤

# 正確使用：實作子類別
dog = Dog()
cat = Cat()

print(dog.make_sound())  # Woof!
print(cat.make_sound())  # Meow!