code: def test_empty_list_in_map_elements() -> None:
      df = pl.DataFrame(
          {
              "a": [[1], [1, 2], [3, 4], [5, 6]],
              "b": [[3], [1, 2], [1, 2], [4, 5]],
          }
      )
  
      assert df.select(
          pl.struct(["a", "b"]).map_elements(
              lambda row: list(set(row["a"]) & set(row["b"]))
          )
      ).to_dict(as_series=False) == {"a": [[], [1, 2], [], [5]]}
  
imports: from __future__ import annotations
  import json
  from datetime import date, datetime, timedelta
  import numpy
  import pytest
  import polars
  from polars.exceptions import PolarsInefficientMapWarning
  from polars.testing import assert_frame_equal
label_desc: Use image node_id 9 for calling a global function with example usage: test_empty_list_in_map_elements() without return types