code: def test_concatenate_rows_of_lists():
      pdf = pd.DataFrame({"val": [["a", "a"], ["b"], ["c"]]})
      gdf = cudf.from_pandas(pdf)
  
      expect = pdf["val"] + pdf["val"]
      got = gdf["val"] + gdf["val"]
  
      assert_eq(expect, got)
  
imports: import functools
  import operator
  import numpy
  import pandas
  import pyarrow
  import pytest
  import cudf
  from cudf import NA
  from cudf._lib.copying import get_element
  from cudf.api.types import is_scalar
  from cudf.testing._utils import DATETIME_TYPES, NUMERIC_TYPES, TIMEDELTA_TYPES, assert_eq
label_desc: Use image node_id 29 for calling a global function with example usage: test_concatenate_rows_of_lists() without return types