code: def test_basic(self):
      df = pd.DataFrame(
          {
              "a": [1, 2, 3, 4],
              "b": [5, 6, 7, 8],
          }
      )
      ds = ray.data.from_pandas(df)
      prep = Concatenator(output_column_name="c")
      new_ds = prep.transform(ds)
      for i, row in enumerate(new_ds.take()):
          assert np.array_equal(row["c"], np.array([i + 1, i + 5]))
  
file_path: ray/python/ray/data/tests/preprocessors/test_concatenator.py
imports: import numpy
  import pandas
  import pytest
  import ray
  from ray.data.preprocessors import Concatenator
label_desc: Use image node_id 1 for calling the TestConcatenator obj's underlying member method code with example usage: obj.test_basic() without return types