code: def test_structured_data_get_col_names_from_df(fit, tmp_path):
      clf = ak.StructuredDataClassifier(
          directory=tmp_path,
          seed=test_utils.SEED,
      )
      clf.fit(x=test_utils.TRAIN_CSV_PATH, y="survived")
  
      assert nest.flatten(clf.inputs)[0].column_names[0] == "sex"
  
file_path: autokeras/autokeras/tasks/structured_data_test.py
imports: from unittest import mock
  import numpy
  import pandas
  import pytest
  from tensorflow import nest
  import autokeras
  from autokeras import test_utils
label_desc: Use image node_id 4 for calling a global function with example usage: test_structured_data_get_col_names_from_df(fit, tmp_path) without return types