How to convert customRender to TagExtension

[Munsif-Ali]

i have updated the package to 3.x.x and now the customRender Property is not available and the documentation says that i can use TagExtension instead of that how can i convert this code (in this i need child and in TagExtension i don't have access to child) to TagExtension

 customRender: {"embed": (RenderContext renderContext, Widget child) {
        var videoLink = renderContext.parser.htmlData.text
             .splitBetween('<embed>', '</embed');
       if (videoLink.contains('yout')) {
             return YouTubeEmbedWidget(
                 videoLink.replaceAll('<br>', '').convertYouTubeUrlToId());
           } else if (videoLink.contains('vimeo')) {
             return VimeoEmbedWidget(videoLink.replaceAll('<br>', ''));
           } else {
             return child;
           }
         }
}