code: def test_continuous_cvls_efficient(self):
      nobs = 500
      np.random.seed(12345)
      C1 = np.random.normal(size=(nobs,))
      C2 = np.random.normal(2, 1, size=(nobs,))
      b0 = 3
      b1 = 1.2
      b2 = 3.7  # regression coefficients
      Y = b0 + b1 * C1 + b2 * C2
  
      model_efficient = nparam.KernelReg(
          endog=[Y],
          exog=[C1],
          reg_type="lc",
          var_type="c",
          bw="cv_ls",
          defaults=nparam.EstimatorSettings(efficient=True, n_sub=100),
      )
  
      model = nparam.KernelReg(
          endog=[Y], exog=[C1], reg_type="ll", var_type="c", bw="cv_ls"
      )
      npt.assert_allclose(
          model.bw, model_efficient.bw, atol=5e-2, rtol=1e-1
      )
  
imports: import pytest
  import numpy
  import numpy.testing
  import statsmodels.api
label_desc: Use image node_id 7 for calling the TestKernelReg obj's underlying member method code with example usage: obj.test_continuous_cvls_efficient() without return types