marimo writeCapture widget

wc.html

<script>
// add now so ad can begin rendering
marimo.add_widget({
    widget_prototype:'writecapture_widget',
    id: "some_ad",
    html: '<script src="/my/ad/server.js"></script>',
});
</script>
<!-- ... -->
<div id="some_ad"></div>
<script>
    // this will trigger the sanitized ad to be painted to the DOM
    marimo.emit('some_ad_ready');
</script>