How to use the rhino3dm.UnitSystem.UnitScale function in rhino3dm

model = None

    try:
        model = r3d.File3dm.Read(filepath)
    except:
        print("Failed to import .3dm model: {}".format(filepath))
        return {'CANCELLED'}

    top_collection_name = os.path.splitext(os.path.basename(filepath))[0]
    if top_collection_name in context.blend_data.collections.keys():
        toplayer = context.blend_data.collections[top_collection_name]
    else:
        toplayer = context.blend_data.collections.new(name=top_collection_name)

    # Get proper scale for conversion
    scale = r3d.UnitSystem.UnitScale(model.Settings.ModelUnitSystem, r3d.UnitSystem.Meters) / context.scene.unit_settings.scale_length

    layerids = {}
    materials = {}

    # Parse options
    import_views = options.get("import_views", False)
    import_named_views = options.get("import_named_views", False)
    import_hidden_objects = options.get("import_hidden_objects", False)
    import_hidden_layers = options.get("import_hidden_layers", False)
    import_groups = options.get("import_groups", False)
    import_nested_groups = options.get("import_nested_groups", False)
    import_instances = options.get("import_instances",False)
    update_materials = options.get("update_materials", False)


    # Import Views and NamedViews