code: def _is_git_repo(dir):
      """Returns True if `dir` is managed under a Git repo."""
      return (
          file_util.find_up(os.path.join(".git", "HEAD"), dir)
          is not None
      )
  
imports: import collections
  import logging
  import re
  import os
  import subprocess
  from guild import config
  from guild import file_util
  from guild import util
  from guild.file_util import FileSelectRule
label_desc: Use image node_id 20 for calling a global function with example usage: _is_git_repo(dir) and returns: unknown