Visitor Pattern in Python: Double Dispatch Demo

class Animal:
    def accept(self, visitor):
        visitor.visit(self)

class Dog(Animal):
    def speak(self):
        return "Woof!"

class Cat(Animal):
    def speak(self):
        return "Meow!"

class SoundVisitor:
    def visit(self, animal):
        if isinstance(animal, Dog):
            return self.visit_dog(animal)
        elif isinstance(animal, Cat):
            return self.visit_cat(animal)

    def visit_dog(self, dog):
        return f"Dog says: {dog.speak()}"

    def visit_cat(self, cat):
        return f"Cat says: {cat.speak()}"

class NameVisitor:
    def visit(self, animal):
        if isinstance(animal, Dog):
            return self.visit_dog(animal)
        elif isinstance(animal, Cat):
            return self.visit_cat(animal)

    def visit_dog(self, dog):
        return "It's a dog!"

    def visit_cat(self, cat):
        return "It's a cat!"

if __name__ == "__main__":
    animals = [Dog(), Cat()]
    sound_visitor = SoundVisitor()
    name_visitor = NameVisitor()

    for animal in animals:
        print(animal.accept(sound_visitor))
        print(animal.accept(name_visitor))