docs: def post_commit_hook(argv):
      """Hook: for checking commit message."""
      _, stdout, _ = run("git log -1 --format=%B HEAD")
      message = "\n".join(stdout)
      options = {"allow_empty": True}
  
      if not _check_message(message, options):
          click.echo(
              "Commit message errors (fix with 'git commit --amend').",
              file=sys.stderr)
          return 1  # it should not fail with exit
      return 0