code: def setup_class(cls):
      super().setup_class()  # initialize DGP
  
      y, x, exog = cls.y, cls.x, cls.exog
      nobs = y.shape[0]
      weights = np.ones(nobs)
      weights[: nobs // 3] = 0.1
      weights[-nobs // 5 :] = 2
  
      # use order = 2 in regression
      pmod = smoothers.PolySmoother(2, x)
      pmod.fit(y, weights=weights)  # no return
  
      cls.res_ps = pmod
      cls.res2 = WLS(y, exog[:, : 2 + 1], weights=weights).fit()
  
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 1 for calling the TestPolySmoother3 obj's underlying member method code with example usage: obj.setup_class(cls) without return types