code: def test_top_k_descending() -> None:
      df = pl.DataFrame({"a": [1, 2, 3], "b": [4, 5, 6]})
      result = df.top_k(1, by=["a", "b"], descending=True)
      expected = pl.DataFrame({"a": [1], "b": [4]})
      assert_frame_equal(result, expected)
      result = df.top_k(1, by=["a", "b"], descending=[True, True])
      assert_frame_equal(result, expected)
      with pytest.raises(
          ValueError,
          match=r"the length of `descending` \(1\) does not match the length of `by` \(2\)",
      ):
          df.top_k(1, by=["a", "b"], descending=[True])
  
imports: from __future__ import annotations
  from datetime import date, datetime
  from typing import Any
  import pytest
  import polars
  from polars.testing import assert_frame_equal, assert_series_equal
label_desc: Use image node_id 30 for calling a global function with example usage: test_top_k_descending() without return types