append_html = function (html, md, element) {
        var type = 'text/html';
        var toinsert = this.create_output_subarea(md, "output_html rendered_html", type);
        this.keyboard_manager.register_events(toinsert);
        toinsert.append(html);
        element.append(toinsert);
        require(['observable'], function (Observable) {
          Observable.scopedEval(toinsert)();
        });

        //eval($(element).find("script").text())
        return toinsert;
    }
safely append an item to the document
this is an object created by user code,
and may have errors, which should not be raised
under any circumstances.