docs: def html_to_valid_cnxml(html_source):
      """Transform the HTML to valid CNXML (used for OERPUB).
      No original CNXML is needed.  If HTML is from Aloha please use
      aloha_to_html before using this method
      """
      source = _string2io(html_source)
      xml = etree.parse(source)
      return etree_to_valid_cnxml(xml, pretty_print=True)