code: def git_timestamp(path):
      if not os.path.isfile(path):
          return None
  
      # Files that are in the git index are considered most recent
      if file_in_git_index(path):
          return float("inf")
  
      # Return the commit timestamp
      try:
          git_ts_str = system(
              "git", "log", "-1", "--pretty=%ct", path
          ).strip()
      except SystemExit as err:
          if err.code == 128:
              # git not initialized
              git_ts_str = ""
          else:
              raise
  
      if git_ts_str:
          return float(git_ts_str)
  
      # The file is not in the git index
      return get_timestamp(path)
  
imports: import argparse
  import glob
  import json
  import os
  import re
  import shlex
  import subprocess
  import sys
  import warnings
  from copy import copy
  from tempfile import NamedTemporaryFile
  from .combine import combine_inputs_with_outputs
  from .compare import NotebookDifference, compare, test_round_trip_conversion
  from .config import load_jupytext_config, notebook_formats
  from .formats import _BINARY_FORMAT_OPTIONS, _VALID_FORMAT_OPTIONS, JUPYTEXT_FORMATS, check_auto_ext, check_file_version, long_form_multiple_formats, long_form_one_format, short_form_one_format
  from .header import recursive_update
  from .jupytext import create_prefix_dir, read, reads, write, writes
  from .kernels import find_kernel_specs, get_kernel_spec, kernelspec_from_language
  from .languages import _SCRIPT_EXTENSIONS
  from .paired_paths import InconsistentPath, base_path, find_base_path_and_format, full_path, paired_paths
  from .pairs import latest_inputs_and_outputs, read_pair, write_pair
  from .version import __version__
label_desc: Use image node_id 13 for calling a global function with example usage: git_timestamp(path) and returns: get_timestamp, None, float, float