TN 1

example.ts

class Dog {
  bark = () => {
    console.log('bark!');
  };
}

class Cat {
  meow = () => {
    console.log('meow!');
  };
}

function sound(animal: Dog | Cat) {
  if (animal instanceof Dog) {
    animal.bark();
    animal.meow();
    return;
  }
  if (animal instanceof Cat) {
    animal.bark();
    animal.meow();
    return;
  }

  animal.bark();
  animal.meow();
}