code: def test_pdf(self):
      scale = getattr(self, "scale", 1)
      x = np.linspace(-4, 4, 11) * scale
      pdf2 = self.dist2.pdf(x)
      pdf1 = self.dist1.pdf(x)
      atol_pdf = getattr(self, "atol_pdf", 0)
      assert_allclose(
          ((pdf2 - pdf1) ** 2).mean(), 0, rtol=1e-6, atol=atol_pdf
      )
      assert_allclose(pdf2, pdf1, rtol=1e-6, atol=atol_pdf)
  
file_path: statsmodels/statsmodels/sandbox/distributions/tests/test_norm_expan.py
imports: import pytest
  import numpy
  from scipy import stats
  from numpy.testing import assert_allclose, assert_array_less
  from statsmodels.sandbox.distributions.extras import NormExpan_gen
label_desc: Use image node_id 1 for calling the CheckExpandNorm obj's underlying member method code with example usage: obj.test_pdf() without return types