code: def hash_blocks(text, hashes):
      
      def sub(match):
          block = match.group(1)
          hashed = hash_text(block, 'block')
          hashes[hashed] = block
          return '\n\n' + hashed + '\n\n'
      return re_block.sub(sub, text)
docs: Hashes HTML block tags.
  
      PARAMETERS:
      text   -- str; Markdown text
      hashes -- dict; a dictionary of all hashes, where keys are hashes
                and values are their unhashed versions.
  
      When HTML block tags are used, all content inside the tags is
      preserved as-is, without any Markdown processing. See block_tags
      for a list of block tags.