code: def test_pandas_roundtrip(ray_start_regular_shared, tmp_path):
      df1 = pd.DataFrame({"one": [1, 2, 3], "two": ["a", "b", "c"]})
      df2 = pd.DataFrame({"one": [4, 5, 6], "two": ["e", "f", "g"]})
      ds = ray.data.from_pandas([df1, df2])
      dfds = ds.to_pandas()
      assert pd.concat([df1, df2], ignore_index=True).equals(dfds)
  
file_path: ray/python/ray/data/tests/test_pandas.py
imports: import numpy
  import pandas
  import pyarrow
  import pytest
  import ray
  from ray.data.extensions import ArrowTensorArray, ArrowTensorType, TensorDtype
  from ray.data.tests.conftest import *
  from ray.data.tests.mock_http_server import *
  from ray.tests.conftest import *
label_desc: Use image node_id 5 for calling a global function with example usage: test_pandas_roundtrip(ray_start_regular_shared, tmp_path) without return types