code: def test_map_elements_infer_list() -> None:
      df = pl.DataFrame(
          {
              "int": [1, 2],
              "str": ["a", "b"],
              "bool": [True, None],
          }
      )
      assert (
          df.select([pl.all().map_elements(lambda x: [x])]).dtypes
          == [pl.List] * 3
      )
  
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 1 for calling a global function with example usage: test_map_elements_infer_list() without return types