class_docstr: Override `HTMLExtractor` and create `etree` `Elements` for any elements which should have content parsed as
  Markdown.
docstr: Handle any buffered data.
code: def close(self):
      """Handle any buffered data."""
      super().close()
      # Handle any unclosed tags.
      if self.mdstack:
          # Close the outermost parent. `handle_endtag` will close all unclosed children.
          self.handle_endtag(self.mdstack[0])
  
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 3 for calling the HTMLExtractorExtra obj's underlying member method code with example usage: obj.close() without return types