code: def derive_toctree_rst(self, current_file):
          
          TAB = " " * 4
          lines = list()
          lines.append(".. toctree::")
          for opt in TocTree.option_spec:
              value = self.options.get(opt)
              if value is not None:
                  lines.append(("{}:{}: {}".format(TAB, opt, value)).rstrip())
          lines.append("")
  
          append_ahead = "append_ahead" in self.options
          if append_ahead:
              for line in list(self.content):
                  lines.append(TAB + line)
  
          article_folder = ArticleFolder(dir_path=Path(current_file).parent.abspath)
          for af in article_folder.sub_article_folders:
              line = "{}{} <{}>".format(TAB, af.title, af.rel_path)
              lines.append(line)
  
          append_behind = not append_ahead
          if append_behind:
              for line in list(self.content):
                  lines.append(TAB + line)
  
          lines.append("")
          return "\n".join(lines)
docs: Generate the rst content::
  
              .. toctree::
                  args ...
  
                  example.rst
                  ...
  
          :param current_file:
          :return: