code: def test_first_last_unit_length_12363() -> None:
      df = pl.DataFrame(
          {
              "a": [1, 2],
              "b": [None, None],
          }
      )
  
      assert df.select(
          pl.all().drop_nulls().first().name.suffix("_first"),
          pl.all().drop_nulls().last().name.suffix("_last"),
      ).to_dict(as_series=False) == {
          "a_first": [1],
          "b_first": [None],
          "a_last": [2],
          "b_last": [None],
      }
  
imports: from __future__ import annotations
  from datetime import date, datetime, timedelta
  from typing import TYPE_CHECKING, Any
  import numpy
  import pytest
  import polars
  from polars.testing import assert_frame_equal
label_desc: Use image node_id 20 for calling a global function with example usage: test_first_last_unit_length_12363() without return types