code: def _register(self, md: markdown.Markdown) -> None:
      md.treeprocessors.register(self, "relpath", 0)
  
imports: from __future__ import annotations
  import copy
  import enum
  import logging
  import posixpath
  import warnings
  from typing import TYPE_CHECKING, Any, Callable, Iterator, MutableMapping, Sequence
  from urllib.parse import unquote
  from urllib.parse import urljoin, urlsplit, urlunsplit
  import markdown
  import markdown.htmlparser
  import markdown.postprocessors
  import markdown.treeprocessors
  from markdown.util import AMP_SUBSTITUTE
  from mkdocs import utils
  from mkdocs.structure import StructureItem
  from mkdocs.structure.toc import get_toc
  from mkdocs.utils import _removesuffix, get_build_date, get_markdown_title, meta, weak_property
label_desc: Use image node_id 6 for calling the _RelativePathTreeprocessor obj's underlying member method code with example usage: obj._register(md) without return types