code: def test_csv_roundtrip_backend_dispatch(tmp_path):
      # Test ddf.read_csv cudf-backend dispatch
      df = cudf.DataFrame(
          {"x": [1, 2, 3, 4], "id": ["a", "b", "c", "d"]}
      )
      ddf = dask_cudf.from_cudf(df, npartitions=2)
      csv_path = str(tmp_path / "data-*.csv")
      ddf.to_csv(csv_path, index=False)
      with dask.config.set({"dataframe.backend": "cudf"}):
          ddf2 = dd.read_csv(csv_path)
      assert isinstance(ddf2, dask_cudf.DataFrame)
      dd.assert_eq(ddf, ddf2, check_divisions=False, check_index=False)
  
imports: import gzip
  import os
  import warnings
  import numpy
  import pandas
  import pytest
  import dask
  from dask import dataframe
  import cudf
  import dask_cudf
label_desc: Use image node_id 3 for calling a global function with example usage: test_csv_roundtrip_backend_dispatch(tmp_path) without return types