code: def test_ci(self):
      res_wls = self.res_wls
      prstd, iv_l, iv_u = wls_prediction_std(res_wls)
      pred_res = get_prediction(res_wls)
      ci = pred_res.conf_int(obs=True)
  
      assert_allclose(pred_res.se_obs, prstd, rtol=1e-13)
      assert_allclose(ci, np.column_stack((iv_l, iv_u)), rtol=1e-13)
  
      sf = pred_res.summary_frame()
  
      col_names = [
          "mean",
          "mean_se",
          "mean_ci_lower",
          "mean_ci_upper",
          "obs_ci_lower",
          "obs_ci_upper",
      ]
      assert_equal(sf.columns.tolist(), col_names)
  
      pred_res2 = res_wls.get_prediction()
      ci2 = pred_res2.conf_int(obs=True)
  
      assert_allclose(pred_res2.se_obs, prstd, rtol=1e-13)
      assert_allclose(ci2, np.column_stack((iv_l, iv_u)), rtol=1e-13)
  
      sf2 = pred_res2.summary_frame()
      assert_equal(sf2.columns.tolist(), col_names)
  
      # check that list works, issue 4437
      x = res_wls.model.exog.mean(0)
      pred_res3 = res_wls.get_prediction([x])
      ci3 = pred_res3.conf_int(obs=True)
      pred_res3b = res_wls.get_prediction(x.tolist())
      ci3b = pred_res3b.conf_int(obs=True)
      assert_allclose(pred_res3b.se_obs, pred_res3.se_obs, rtol=1e-13)
      assert_allclose(ci3b, ci3, rtol=1e-13)
      res_df = pred_res3b.summary_frame()
      assert_equal(res_df.index.values, [0])
  
      x = res_wls.model.exog[-2:]
      pred_res3 = res_wls.get_prediction(x)
      ci3 = pred_res3.conf_int(obs=True)
      pred_res3b = res_wls.get_prediction(x.tolist())
      ci3b = pred_res3b.conf_int(obs=True)
      assert_allclose(pred_res3b.se_obs, pred_res3.se_obs, rtol=1e-13)
      assert_allclose(ci3b, ci3, rtol=1e-13)
      res_df = pred_res3b.summary_frame()
      assert_equal(res_df.index.values, [0, 1])
  
file_path: statsmodels/statsmodels/regression/tests/test_predict.py
imports: import numpy
  from numpy.testing import assert_allclose, assert_equal
  import pandas
  from statsmodels.regression.linear_model import OLS, WLS
  from statsmodels.sandbox.regression.predstd import wls_prediction_std
  from statsmodels.regression._prediction import get_prediction
label_desc: Use image node_id 2 for calling the TestWLSPrediction obj's underlying member method code with example usage: obj.test_ci() without return types