code: def insert_code(filename, code, save=True, marker='# ATX CODE END'):
      
      content = ''
      found = False
      for line in open(filename, 'rb'):
          if not found and line.strip() == marker:
              found = True
              cnt = line.find(marker)
              content += line[:cnt] + code
          content += line
      if not found:
          if not content.endswith('\n'):
              content += '\n'
          content += code + marker + '\n'
      if save:
          with open(filename, 'wb') as f:
              f.write(content)
      return content
docs: Auto append code