code: def test_cross_section_exceptions():
      y = np.random.standard_normal(1000)
      x = np.random.standard_normal((1000, 2))
      with pytest.raises(ValueError, match="trend must be one of "):
          _cross_section(y, x, "unknown")
  
file_path: arch/arch/tests/unitroot/test_engle_granger.py
imports: import numpy
  from numpy.testing import assert_allclose
  import pandas
  import pytest
  from statsmodels.iolib.summary import Summary
  from arch.unitroot._engle_granger import engle_granger_cv, engle_granger_pval
  from arch.unitroot._shared import ResidualCointegrationTestResult, _cross_section
  from arch.unitroot.cointegration import engle_granger
label_desc: Use image node_id 11 for calling a global function with example usage: test_cross_section_exceptions() without return types