class Cake {
  constructor(type, flavour) {
    this.type = type;
    this.flavour = flavour;
  }

  addCherry() {
    this.isCherryAdded = true;
  }
}

const vanillaCake = new Cake('butter', 'vanilla');

const chocolateCake = new Cake('sponge', 'chocolate');

vanillaCake.addCherry();
console.log(vanillaCake.isCherryAdded); //returns true