code: def test_list_null_list_categorical_cast() -> None:
      expected = pl.List(pl.Categorical)
      s = pl.Series([[]], dtype=pl.List(pl.Null)).cast(expected)
      assert s.dtype == expected
      assert s.to_list() == [[]]
  
imports: from __future__ import annotations
  import pickle
  from datetime import date, datetime, time
  from typing import TYPE_CHECKING, Any
  import pandas
  import pytest
  import polars
  from polars.testing import assert_frame_equal, assert_series_equal
label_desc: Use image node_id 33 for calling a global function with example usage: test_list_null_list_categorical_cast() without return types