public void SendInAppPurchase_OnClick()
    {
        var attributes = new Dictionary <string, object>()
        {
            ["key1"] = "value1",
            ["key2"] = "value2"
        };

        // Instead of sending a real product we create a fake one for testing.
        // In your production environment, the Product object should be received from the Unity Purchasing API.
        Product product = BuildProduct();

        SingularSDK.InAppPurchase("Test IAP", product, attributes);

        ShowToast("IAP sent");
    }