class Person {
	protected name: string;
	protected constructor(theName: string) {
		this.name = theName;
	}
}

class Employee extends Person {
	private department: string;

	constructor(name: string, department: string) {
		super(name);
		this.department = department;
	}

	public getElevatorPitch() {
		return `Hello, my name is ${this.name} and I work in ${this.department}.`;
	}
}
let howard = new Employee('Howard', 'Sales');
let john = new Person('John');
// constructor of class 'Person' is protected and only  accessible within the class declaration.