code: def test_fetch_union(tmp_path: Path) -> None:
      tmp_path.mkdir(exist_ok=True)
  
      df1 = pl.DataFrame({"a": [0, 1, 2], "b": [1, 2, 3]})
      df2 = pl.DataFrame({"a": [3, 4, 5], "b": [4, 5, 6]})
  
      file_path_1 = tmp_path / "df_fetch_1.parquet"
      file_path_2 = tmp_path / "df_fetch_2.parquet"
      file_path_glob = tmp_path / "df_fetch_*.parquet"
  
      df1.write_parquet(file_path_1)
      df2.write_parquet(file_path_2)
  
      result_one = pl.scan_parquet(file_path_1).fetch(1)
      result_glob = pl.scan_parquet(file_path_glob).fetch(1)
  
      expected = pl.DataFrame({"a": [0], "b": [1]})
      assert_frame_equal(result_one, expected)
  
      # Both fetch 1 per file or 1 per dataset would be ok, as we don't guarantee anything
      # currently we have one per dataset.
      expected = pl.DataFrame({"a": [0], "b": [1]})
      assert_frame_equal(result_glob, expected)
  
imports: from __future__ import annotations
  import io
  from datetime import datetime, time, timezone
  from decimal import Decimal
  from typing import TYPE_CHECKING
  import numpy
  import pandas
  import pyarrow
  import pyarrow.dataset
  import pyarrow.parquet
  import pytest
  import polars
  from polars.testing import assert_frame_equal, assert_series_equal
label_desc: Use image node_id 22 for calling a global function with example usage: test_fetch_union(tmp_path) without return types