code: def test_list_null_constructor_schema() -> None:
      expected = pl.List(pl.Null)
      assert pl.Series([[]]).dtype == expected
      assert pl.Series([[]], dtype=pl.List).dtype == expected
      assert pl.DataFrame({"a": [[]]}).dtypes[0] == expected
      assert pl.DataFrame(schema={"a": pl.List}).dtypes[0] == expected
  
imports: from __future__ import annotations
  from collections import OrderedDict
  from datetime import date, timedelta
  from typing import Any, Iterator, Mapping
  import pytest
  import polars
  from polars.testing import assert_frame_equal, assert_series_equal
label_desc: Use image node_id 34 for calling a global function with example usage: test_list_null_constructor_schema() without return types