code: def test_selector_startswith(df: pl.DataFrame) -> None:
      assert df.select(cs.starts_with("a")).columns == ["abc"]
      assert df.select(cs.starts_with("ee")).columns == ["eee"]
      assert df.select(
          cs.starts_with("d", "e", "f", "g", "h", "i", "j")
      ).columns == [
          "def",
          "eee",
          "fgg",
          "ghi",
      ]
      assert df.select(
          ~cs.starts_with("d", "e", "f", "g", "h", "i", "j")
      ).columns == [
          "abc",
          "bbb",
          "cde",
          "JJK",
          "Lmn",
          "opp",
          "qqR",
      ]
  
imports: from typing import Any
  import pytest
  import polars
  import polars.selectors
  from polars.selectors import expand_selector, is_selector
  from polars.testing import assert_frame_equal
label_desc: Use image node_id 18 for calling a global function with example usage: test_selector_startswith(df) without return types