code: def test_index_expr_with_literal() -> None:
      df = pl.DataFrame({"a": [1, 2, 3], "b": ["a", "b", "c"]}).sort(
          "a"
      )
      out = df.rolling(
          index_column=(5 * pl.col("a")).set_sorted(), period="2i"
      ).agg(pl.col("b"))
      expected = pl.DataFrame(
          {"literal": [5, 10, 15], "b": [["a"], ["b"], ["c"]]}
      )
      assert_frame_equal(out, expected)
  
imports: from __future__ import annotations
  from datetime import date, datetime, timedelta
  from typing import TYPE_CHECKING
  import numpy
  import pytest
  from numpy import nan
  import polars
  from polars.exceptions import ComputeError
  from polars.testing import assert_frame_equal, assert_series_equal
label_desc: Use image node_id 26 for calling a global function with example usage: test_index_expr_with_literal() without return types