code: def test_normalization(self):
      # GH 5517
      evec = self.res.evec
      non_zero = evec.flat != 0
      assert evec.flat[non_zero][0] > 0
  
imports: import os
  import warnings
  import numpy
  from numpy.testing import assert_almost_equal, assert_equal
  import pandas
  import pytest
  from statsmodels.tools.sm_exceptions import HypothesisTestWarning
  from statsmodels.tsa.vector_ar.vecm import coint_johansen
label_desc: Use image node_id 4 for calling the CheckCointJoh obj's underlying member method code with example usage: obj.test_normalization() without return types