code: def test_concat_horizontal_single_df(lazy: bool) -> None:
      a = pl.DataFrame({"a": ["a", "b"], "b": [1, 2]})
  
      if lazy:
          out = pl.concat([a.lazy()], how="horizontal").collect()
      else:
          out = pl.concat([a], how="horizontal")
  
      expected = a
      assert_frame_equal(out, expected)
  
imports: from __future__ import annotations
  from datetime import timedelta
  from typing import TYPE_CHECKING
  import numpy
  import pytest
  import polars
  from polars.testing import assert_frame_equal, assert_series_equal
label_desc: Use image node_id 5 for calling a global function with example usage: test_concat_horizontal_single_df(lazy) without return types