docs: function makeCoffee() {
      judge(arguments, function(sugars, flavor, size, callback) {
          var msg = size + " cup of " + flavor + " coffe with " + sugars + " sugars.";
          // you can be sure that callback is indeed a function:
          callback(msg);
      }, function(err) {
          console.log("Invalid arguments: " + err);
      });
  }