docs: def html(self, selector):
          """Return html result that executed by given css selector
  
          :param selector: `str` css selector
          :return: `list` or `None`
          """
  
          result = self.__bs4.select(selector)
  
          return [str(r) for r in result] \
              if result.__len__() > 1 else \
              str(result[0]) if result.__len__() > 0 else None