Add existing levels to World through Python

How could I add existing levels to a World via Python? This is my most recent attempt:

loaded_level = unreal.EditorLoadingAndSavingUtils.load_map(level_path)
    if loaded_level is not None:
        world = unreal.EditorLevelLibrary.get_editor_world()
        unreal.EditorLevelUtils.add_level_to_world(world, level_path, unreal.LevelStreamingAlwaysLoaded)

I was having issues because I was creating a World object. What I ended up doing was simply creating a new Level so for anyone reading this later, the correct steps are:

path = "/Game/..."
level_editor_subsystem = unreal.get_editor_subsystem(unreal.LevelEditorSubsystem)
unreal_editor = unreal.get_editor_subsystem(unreal.UnrealEditorSubsystem)
world = unreal_editor.get_editor_world()
sublevel_path = "/Game/..."
unreal.EditorLevelUtils.add_level_to_world(world, sublevel_path, unreal.LevelStreamingAlwaysLoaded)
# save