docs: def include_codemirror(self):
          """Include resources in pages"""
          contents = []
          # base
          js = self._get_tag('codemirror.js', 'script')
          css = self._get_tag('codemirror.css', 'stylesheet')
          if js and css:
              contents.append(js)
              contents.append(css)
          # languages
          for language in self.languages:
              url = self.__class__.LANGUAGE_REL_URL.format(language)
              js = self._get_tag(url, 'script')
              if js:
                  contents.append(js)
          # theme
          if self.theme:
              url = self.__class__.THEME_REL_URL.format(self.theme)
              css = self._get_tag(url, 'stylesheet')
              if css:
                  contents.append(css)
          # addons
          if self.addons:
              # add to list
              for addon_type, name in self.addons:
                  url = self.__class__.ADDON_REL_URL.format(addon_type, name)
                  js = self._get_tag(url, 'script')
                  if js:
                      contents.append(js)
                  # if there is a css file relative to this addon
                  url = self.__class__.ADDON_CSS_REL_URL.format(addon_type, name)
                  css = self._get_tag(url, 'stylesheet', False)
                  if css:
                      contents.append(css)
          # return html
          return Markup('\n'.join(contents))