function requestPhoneCost () {
    var product = "iPhone 7";
    server.requestPrice(product);
}

server.onResponse(function(response) {
   //response contains only information about the price, but not
   //what product its for

   showResult( , response.price);

});

function showResult (product, cost) {
   alert(product + " costs " + response + "dollars");
}