CLEAN.G23.right.swift

class Animal {
    func makeNoise() {
        print("Unknown animal!")
    }
}

class Dog: Animal {
    override func makeNoise() {
        print("The dog goes woof!")
    }
}

class Cat: Animal {
    override func makeNoise() {
        print("The cat goes meow!")
    }
}

class Bird: Animal {
    override func makeNoise() {
        print("The bird goes tweet!")
    }
}

func makeNoise(animal: Animal) {
    animal.makeNoise()
}