code: def extendMarkdown(self, md):
      md.treeprocessors.register(
          _AddCodeTagTreeprocessor(), "add-code-tag", 40
      )
  
imports: from markdown.test_tools import TestCase
  from markdown.extensions.codehilite import CodeHiliteExtension, CodeHilite
  from markdown import extensions, treeprocessors
  import os
  import xml.etree.ElementTree
label_desc: Use image node_id 1 for calling the _ExtensionThatAddsAnEmptyCodeTag obj's underlying member method code with example usage: obj.extendMarkdown(md) without return types