tocSection.append("<h2>Table Of Contents</h2>");
        Element toc = tocSection.append("<ul class='toc'/>").children().last();

        Elements h23elements = document.select("h2,h3");
        for (Element h23element: h23elements) {
            String tag = h23element.tagName();
            String name = h23element.text();

   * `INADEQUATE_SECURITY`.
   */
  HTTP_2("h2"),

  /**
   * Cleartext HTTP/2 with no "upgrade" round trip. This option requires the client to have prior
   * knowledge that the server supports cleartext HTTP/2.
   *
   * See also [Starting HTTP/2 with Prior Knowledge][rfc_7540_34].
   *
   * [rfc_7540_34]: https://tools.ietf.org/html/rfc7540.section-3.4
   */
  H2_PRIOR_KNOWLEDGE("h2_prior_knowledge"),

  /**