code: def test_exog_names(self):
      assert self.model.exog_names == [
          "Intercept",
          "GNPDEFL",
          "GNP",
          "UNEMP",
          "ARMED",
          "POP",
          "YEAR",
      ]
  
imports: from statsmodels.compat.pandas import assert_series_equal
  from io import StringIO
  import warnings
  import numpy
  import numpy.testing
  import pandas
  import patsy
  import pytest
  from statsmodels.datasets import cpunish
  from statsmodels.datasets.longley import load, load_pandas
  from statsmodels.formula.api import ols
  from statsmodels.formula.formulatools import make_hypotheses_matrices
  from statsmodels.tools import add_constant
  from statsmodels.tools.testing import assert_equal
label_desc: Use image node_id 3 for calling the CheckFormulaOLS obj's underlying member method code with example usage: obj.test_exog_names() without return types