private static void BannerDidClickCallback(IntPtr bannerClient)
        {
            YumiBannerClient client = IntPtrToBannerClient(bannerClient);

            if (client.OnAdClick != null)
            {
                client.OnAdClick(client, EventArgs.Empty);
            }
        }
        private static void BannerDidReceiveAdCallback(IntPtr bannerClient)
        {
            YumiBannerClient client = IntPtrToBannerClient(bannerClient);

            if (client.OnAdLoaded != null)
            {
                client.OnAdLoaded(client, EventArgs.Empty);
            }
        }
        private static void BannerDidFailToReceiveAdWithErrorCallback(IntPtr bannerClient, string error)
        {
            YumiBannerClient client = IntPtrToBannerClient(bannerClient);

            if (client.OnAdFailedToLoad != null)
            {
                YumiAdFailedToLoadEventArgs args = new YumiAdFailedToLoadEventArgs()
                {
                    Message = error
                };
                client.OnAdFailedToLoad(client, args);
            }
        }