private void frmProducts_Load(object sender, EventArgs e)
        {
            // wire the event to the method that handles the event
            products.Changed += new ProductList.ChangeHandler(PrintToConsole);

            // add products to the product list
            products.Add("BJWN", "Beginning Java with NetBeans", 57.50m);
            products.Add("CS15", "C# 2015", 56.5m);

            // call the delegate and pass the required argument
            myDelegate(products);
        }
        private void btnAdd_Click(object sender, EventArgs e)
        {
            frmNewProduct newProductForm = new frmNewProduct();
            Product       product        = newProductForm.GetNewProduct();

            if (product != null)
            {
                products.Add(product);
                products.Save();
                FillProductListBox();
            }
        }