code: def test_ols(self):
      # test expectile at q=0.5 versus OLS
  
      res_ols = ols("dens ~ temp + I(temp ** 2.0)", self.df).fit(
          use_t=False
      )
  
      y = res_ols.model.endog
      xx = res_ols.model.exog
  
      mq_norm = norms.MQuantileNorm(0.5, norms.LeastSquares())
      mod_rlm = RLM(y, xx, M=mq_norm)
      res_rlm = mod_rlm.fit()
  
      assert_allclose(res_rlm.params, res_ols.params, rtol=1e-10)
      assert_allclose(res_rlm.bse, res_ols.bse, rtol=1e-10)
      assert_allclose(res_rlm.pvalues, res_ols.pvalues, rtol=1e-10)
  
file_path: statsmodels/statsmodels/robust/tests/test_mquantiles.py
imports: import numpy
  from numpy.testing import assert_allclose
  import pandas
  from statsmodels.regression.linear_model import OLS
  from statsmodels.regression.quantile_regression import QuantReg
  from statsmodels.robust import norms
  from statsmodels.robust.robust_linear_model import RLM
label_desc: Use image node_id 2 for calling the TestMQuantiles obj's underlying member method code with example usage: obj.test_ols() without return types