class_docstr: Override `HTMLExtractor` and create `etree` `Elements` for any elements which should have content parsed as
  Markdown.
code: def handle_data(self, data):
      if self.intail and "\n" in data:
          self.intail = False
      if self.inraw or not self.mdstack:
          super().handle_data(data)
      else:
          self.treebuilder.data(data)
  
imports: from __future__ import annotations
  from .None import Extension
  from ..blockprocessors import BlockProcessor
  from ..preprocessors import Preprocessor
  from ..postprocessors import RawHtmlPostprocessor
  from ..None import util
  from ..htmlparser import HTMLExtractor, blank_line_re
  import xml.etree.ElementTree
  from typing import TYPE_CHECKING, Literal, Mapping
label_desc: Use image node_id 9 for calling the HTMLExtractorExtra obj's underlying member method code with example usage: obj.handle_data(data) without return types