code: def convert_boxed_text_elements(self):
          
          for boxed_text in self.main.getroot().findall('.//boxed-text'):
              sec_el = boxed_text.find('sec')
              if sec_el is not None:
                  sec_el.tag = 'div'
                  title = sec_el.find('title')
                  if title is not None:
                      title.tag = 'b'
                  sec_el.attrib['class'] = 'boxed-text'
                  if 'id' in boxed_text.attrib:
                      sec_el.attrib['id'] = boxed_text.attrib['id']
                  replace(boxed_text, sec_el)
              else:
                  div_el = etree.Element('div', {'class': 'boxed-text'})
                  if 'id' in boxed_text.attrib:
                      div_el.attrib['id'] = boxed_text.attrib['id']
                  append_all_below(div_el, boxed_text)
                  replace(boxed_text, div_el)
docs: Textual material that is part of the body of text but outside the
          flow of the narrative text, for example, a sidebar, marginalia, text
          insert (whether enclosed in a box or not), caution, tip, note box, etc.
  
          <boxed-text> elements for PLoS appear to all contain a single <sec>
          element which frequently contains a <title> and various other content.
          This method will elevate the <sec> element, adding class information as
          well as processing the title.