class Phone {
    model: string
    constructor(model: string) {
        this.model = model
    }
}

class Employee {
    constructor(
        public firstName: string, 
        public lastName: string, 
        public phone: Phone) {}
}

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

let kim = new Employee("Victorya", "Kim",
    new Phone("iPhone 11 Pro"))

console.log(nokiaPhone.model)
console.log(kim.phone.model)