code: def test_vstack_with_nested_nulls() -> None:
      a = pl.DataFrame(
          {"x": [[3.5]]}, schema={"x": pl.List(pl.Float32)}
      )
      b = pl.DataFrame({"x": [[None]]}, schema={"x": pl.List(pl.Null)})
  
      out = a.vstack(b)
      expected = pl.DataFrame(
          {"x": [[3.5], [None]]}, schema={"x": pl.List(pl.Float32)}
      )
      assert_frame_equal(out, expected)
  
file_path: polars/py-polars/tests/unit/dataframe/test_vstack.py
imports: import pytest
  import polars
  from polars.testing import assert_frame_equal
label_desc: Use image node_id 10 for calling a global function with example usage: test_vstack_with_nested_nulls() without return types