code: def _external_repo(
      url,
      rev: Optional[str] = None,
      **kwargs,
  ) -> "Repo":
      logger.debug("Creating external repo %s@%s", url, rev)
      path = _cached_clone(url, rev)
      # Local HEAD points to the tip of whatever branch we first cloned from
      # (which may not be the default branch), use origin/HEAD here to get
      # the tip of the default branch
      rev = rev or "refs/remotes/origin/HEAD"
  
      config = _get_remote_config(url) if os.path.isdir(url) else {}
      config.update({"cache": {"dir": _get_cache_dir(url)}})
      config.update(kwargs.pop("config", None) or {})
  
      main_root = "/"
      repo_kwargs = dict(
          root_dir=path,
          url=url,
          config=config,
          repo_factory=erepo_factory(
              url, main_root, {"cache": config["cache"]}
          ),
          rev=rev,
          **kwargs,
      )
  
      return Repo(**repo_kwargs)
  
imports: import os
  import tempfile
  import threading
  from typing import TYPE_CHECKING, Dict, Optional, Tuple
  from funcy import retry, wrap_with
  from dvc.exceptions import NotDvcRepoError
  from dvc.log import logger
  from dvc.repo import Repo
  from dvc.scm import CloneError, map_scm_exception
  from dvc.utils import relpath
label_desc: Use image node_id 1 for calling a global function with example usage: _external_repo(url, rev) and returns: Repo