code: def test_jupytext_config_cli(tmp_path):
      settings_file = tmp_path / "default_setting_overrides.json"
      system("jupytext-config", "-h")
      system(
          "jupytext-config",
          "--settings-file",
          str(settings_file),
          "set-default-viewer",
          "python",
          "markdown",
      )
      assert "python" in (settings_file).read_text()
      assert "markdown" in system(
          "jupytext-config",
          "--settings-file",
          settings_file,
          "list-default-viewer",
      )
      system(
          "jupytext-config",
          "--settings-file",
          str(settings_file),
          "unset-default-viewer",
          "markdown",
      )
      list_viewers = system(
          "jupytext-config",
          "--settings-file",
          settings_file,
          "list-default-viewer",
      )
      assert "python" in list_viewers
      assert "markdown" not in list_viewers
  
label_desc: Use image node_id 1 for calling a global function with example usage: test_jupytext_config_cli(tmp_path) without return types