code: def git_hash():
      
      if git_repo() is None:
          return "unknown"
      git_hash = subprocess.check_output(
          ["git", "rev-parse", "HEAD"])
      # git_hash is a byte string; we want a string.
      git_hash = git_hash.decode("utf-8")
      # git_hash also comes with an extra \n at the end, which we remove.
      git_hash = git_hash.strip()
      return git_hash
docs: returns the current git hash or unknown if not in git repo