code: def test_coef(self):
      # TODO: check dim of coef
      assert_almost_equal(
          self.res_ps.coef.ravel(), self.res2.params, decimal=14
      )
  
imports: import numpy
  from numpy.testing import assert_almost_equal, assert_equal
  from statsmodels.sandbox.nonparametric import smoothers
  from statsmodels.regression.linear_model import OLS, WLS
label_desc: Use image node_id 2 for calling the CheckSmoother obj's underlying member method code with example usage: obj.test_coef() without return types