class_docstr: Process Markdown Inside HTML Blocks which have been stored in the `HtmlStash`.
code: def run(self, parent: etree.Element, blocks: list[str]) -> bool:
      m = util.HTML_PLACEHOLDER_RE.match(blocks[0])
      if m:
          index = int(m.group(1))
          element = self.parser.md.htmlStash.rawHtmlBlocks[index]
          if isinstance(element, etree.Element):
              # We have a matched element. Process it.
              blocks.pop(0)
              self.parse_element_content(element)
              parent.append(element)
              # Cleanup stash. Replace element with empty string to avoid confusing postprocessor.
              self.parser.md.htmlStash.rawHtmlBlocks.pop(index)
              self.parser.md.htmlStash.rawHtmlBlocks.insert(index, "")
              # Confirm the match to the `blockparser`.
              return True
      # No match found.
      return False
  
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 MarkdownInHtmlProcessor obj's underlying member method code with example usage: obj.run(parent, blocks) and returns: False, True