code: def test_struct_null_cast() -> None:
      dtype = pl.Struct(
          [
              pl.Field("a", pl.Int64),
              pl.Field("b", pl.String),
              pl.Field("c", pl.List(pl.Float64)),
          ]
      )
      assert (
          pl.DataFrame()
          .lazy()
          .select(
              [pl.lit(None, dtype=pl.Null).cast(dtype, strict=True)]
          )
          .collect()
      ).to_dict(as_series=False) == {
          "literal": [{"a": None, "b": None, "c": None}]
      }
  
imports: from __future__ import annotations
  from dataclasses import dataclass
  from datetime import datetime, time
  from typing import TYPE_CHECKING
  import pandas
  import pyarrow
  import pytest
  import polars
  import polars.selectors
  from polars.testing import assert_frame_equal, assert_series_equal
label_desc: Use image node_id 37 for calling a global function with example usage: test_struct_null_cast() without return types