class Animal {}

class Cat extends Animal {}

class BlackCat extends Cat {}

var animal: Animal = new Animal();

var cat: Animal = new Cat();

var blackcat: Animal = new BlackCat();

assert(animal instanceof Animal); // static true

assert(!(animal instanceof Cat)); // dynamic false

assert(!(animal instanceof BlackCat)); // dynamic false

assert(cat instanceof Animal); // static true

assert(cat instanceof Cat); // dynamic true

assert(!(cat instanceof BlackCat)); // dynamic false

assert(blackcat instanceof Animal); // static true

assert(blackcat instanceof Cat); // dynamic true

assert(blackcat instanceof BlackCat); // dynamic true

var nullableAnimal: Animal | null = new Animal();

var nullableCat: Animal | null = new Cat();

var nullableBlackcat: Animal | null = new BlackCat();

assert(nullableAnimal instanceof Animal); // static true

assert(!(nullableAnimal instanceof Cat)); // dynamic false

assert(!(nullableAnimal instanceof BlackCat)); // dynamic false

assert(nullableCat instanceof Animal); // static true

assert(nullableCat instanceof Cat); // dynamic true

assert(!(nullableCat instanceof BlackCat)); // dynamic false

assert(nullableBlackcat instanceof Animal); // static true

assert(nullableBlackcat instanceof Cat); // dynamic true

assert(nullableBlackcat instanceof BlackCat); // dynamic true

var nullAnimal: Animal | null = null;

var nullCat: Animal | null = null;

var nullBlackcat: Animal | null = null;

assert(!(nullAnimal instanceof Animal)); // static false

assert(!(nullAnimal instanceof Cat)); // dynamic false

assert(!(nullAnimal instanceof BlackCat)); // dynamic false

assert(!(nullCat instanceof Animal)); // static false

assert(!(nullCat instanceof Cat)); // dynamic false

assert(!(nullCat instanceof BlackCat)); // dynamic false

assert(!(nullBlackcat instanceof Animal)); // static false

assert(!(nullBlackcat instanceof Cat)); // dynamic false

assert(!(nullBlackcat instanceof BlackCat)); // dynamic false