TypeScript nominal typing for class

gistfile1.txt

/*
// We need an index to generate the "brand" field.
// This correctly handles the inheritance.
class Duck {
  private _0: undefined;
  constructor(public name: string) {
  }
}

class Dog extends Duck {
  private _1: undefined;
  constructor(name: string) { super(name);}
}

function play(duck: Duck, dog: Dog) {
  console.log(`Play with ${duck.name} and ${dog.name}`)
}

const duck = new Duck('Jess')
const dog = new Dog('Loki')
play(duck, dog) // okay

// A 'Dog' is a 'Duck'.
// But a 'Duck' is not a 'Dog': this doesn't compile because of the second duck parameter.
play(dog, duck) // error