function Users(fName, lName) {
this.firstname = fName;
this.lastName = lName;
};

var user1 = new Users("Luka","Tatarishvili");
Users.prototype.fullName = function() {
	return this.fristName + " " + this.lastName;
};

var user2 = new Users("Luka","Tatarishvili");

 it's prototype still has the full name method as a part of it even though we added it after creating object and of course the fullName works ass well on user2 that created after setting prototype