docs: def _convert_markup_basic(self, soup):
          """
          Perform basic conversion of instructions markup. This includes
          replacement of several textual markup tags with their HTML equivalents.
  
          @param soup: BeautifulSoup instance.
          @type soup: BeautifulSoup
          """
          # Inject meta charset tag
          meta = soup.new_tag('meta', charset='UTF-8')
          soup.insert(0, meta)
  
          # 1. Inject basic CSS style
          css = "".join([
              INSTRUCTIONS_HTML_INJECTION_PRE,
              self._mathjax_cdn_url,
              INSTRUCTIONS_HTML_INJECTION_AFTER])
          css_soup = BeautifulSoup(css)
          soup.append(css_soup)
  
          # 2. Replace <text> with <p>
          while soup.find('text'):
              soup.find('text').name = 'p'
  
          # 3. Replace <heading level="1"> with <h1>
          while soup.find('heading'):
              heading = soup.find('heading')
              heading.name = 'h%s' % heading.attrs.get('level', '1')
  
          # 4. Replace <code> with <pre>
          while soup.find('code'):
              soup.find('code').name = 'pre'
  
          # 5. Replace <list> with <ol> or <ul>
          while soup.find('list'):
              list_ = soup.find('list')
              type_ = list_.attrs.get('bullettype', 'numbers')
              list_.name = 'ol' if type_ == 'numbers' else 'ul'