code: def SCM(
      root_dir: str,
      *,
      search_parent_directories: bool = ...,
      no_scm: Literal[True],
  ) -> "NoSCM":
      ...
  
imports: import os
  from contextlib import contextmanager
  from functools import partial
  from typing import TYPE_CHECKING, Iterator, List, Literal, Mapping, Optional, Union, overload
  from funcy import group_by
  from scmrepo.base import Base
  from scmrepo.git import Git
  from scmrepo.noscm import NoSCM
  from dvc.exceptions import DvcException
  from dvc.progress import Tqdm
label_desc: Use image node_id 3 for calling a global function with example usage: SCM(root_dir) without return types