function Phone(model) {
    this.model = model;
}

function Employee(firstName, lastName, phone) {
    this.firstName = firstName;
    this.lastName = lastName;
    this.phone = phone;
}

let nokiaPhone = new Phone("Nokia 6610");

let kim = new Employee("Victorya", "Kim",
    new Phone("iPhone 5"));

console.log(kim.phone.model);