function LoggedCalculator() {
	Calculator.apply(this, arguments);
}


LoggedCalculator.prototype.sum = function(x, y) {
		console.log("Wywołanie metody sum z argumentami " + x + " i " + y);
		var result =  Calculator.prototype.sum(x, y);

		console.log("Wynik działania metody sum: " + result);
		return result;
	};