code: def test_concat_str_wildcard_expansion() -> None:
      # one function requires wildcard expansion the other need
      # this tests the nested behavior
      # see: #2867
  
      df = pl.DataFrame({"a": ["x", "Y", "z"], "b": ["S", "o", "S"]})
      assert df.select(
          pl.concat_str(pl.all()).str.to_lowercase()
      ).to_series().to_list() == ["xs", "yo", "zs"]
  
imports: from __future__ import annotations
  from datetime import date, datetime
  from typing import TYPE_CHECKING
  import pytest
  import polars
  from polars.testing import assert_frame_equal, assert_series_equal
label_desc: Use image node_id 25 for calling a global function with example usage: test_concat_str_wildcard_expansion() without return types