function createImmutable(item){
	let handler = {
		set: function(target, property, value){
			//do nothing, this object is no longer "directly" mutable
			console.log("hey, I'm immutable, you can't set me like this");
		},

		//object is mutable only by invoking a "set_XXXX" method
		//we trap that get and return a function that will create the new object with the mutated property
		//and returns a proxy around the new object, so that immutability continues to work in ensuing assignments
		get: function(target, property, receiver){
			if (property.startsWith("set_")){
				let propName = property.substring(4);
				console.log("assigning to " + propName + " via proxy");
				return function(value){
					//either use the trapped target or "this"
					//let newItem = new target.constructor();
					let newItem = new this.constructor();
					Object.assign(newItem, target);
					//notice I've just doing shallow cloning
					newItem[propName] = value;
					return new Proxy(newItem, handler);
				}

			}
			else{
				return target[property];
			}

		}
	};

	return new Proxy(item, handler);
}

//Let's test it

class Person{
	constructor(name){
		this.name = name;
	}

	say(word){
		return `${word}, I'm ${this.name}`;
  }
}

//--- Main
console.log("started");
let p1 = new Person("Francois");

console.log("p1 says: " + p1.say("hi"));

let immutableP1 = createImmutable(p1);

console.log("immutableP1" + JSON.stringify(immutableP1));
immutableP1.name = "Xuan";
console.log("immutableP1" + JSON.stringify(immutableP1));

let immutableP2 = immutableP1.set_name("Xuan");
console.log("immutableP2" + JSON.stringify(immutableP2));

console.log(immutableP2.say("hi"));

let immutableP3 = immutableP2.set_name("Emmanuel");
console.log("immutableP3" + JSON.stringify(immutableP3));