Potetial Issue with launch file

in https://github.com/ros/urdf_tutorial/blob/ros2/launch/display.launch.py

line 23 ->    ld.add_action(DeclareLaunchArgument(name='model', default_value=str(default_model_path),
                                        description='Path to robot urdf file relative to urdf_tutorial package'))

I belive there shouldn't be the str() there. It prevents the default value from actually working! 