code: def test_pivot_list() -> None:
      df = pl.DataFrame({"a": [1, 2, 3], "b": [[1, 1], [2, 2], [3, 3]]})
  
      expected = pl.DataFrame(
          {
              "a": [1, 2, 3],
              "1": [[1, 1], None, None],
              "2": [None, [2, 2], None],
              "3": [None, None, [3, 3]],
          }
      )
      out = df.pivot(
          "b",
          index="a",
          columns="a",
          aggregate_function="first",
          sort_columns=True,
      )
      assert_frame_equal(out, expected)
  
imports: from __future__ import annotations
  from datetime import date, datetime, timedelta
  from typing import TYPE_CHECKING, Any
  import pytest
  import polars
  import polars.selectors
  from polars.exceptions import ComputeError
  from polars.testing import assert_frame_equal
label_desc: Use image node_id 2 for calling a global function with example usage: test_pivot_list() without return types