code: def test_mixed_mfx_ll_cvls(self, file_name="RegData.csv"):
      nobs = 200
      np.random.seed(1234)
      ovals = np.random.binomial(2, 0.5, size=(nobs,))
      C1 = np.random.normal(size=(nobs,))
      C2 = np.random.normal(2, 1, size=(nobs,))
      noise = np.random.normal(size=(nobs,))
      b0 = 3
      b1 = 1.2
      b2 = 3.7  # regression coefficients
      b3 = 2.3
      Y = b0 + b1 * C1 + b2 * C2 + b3 * ovals + noise
      bw_cv_ls = np.array([1.04726, 1.67485, 0.39852])
      model = nparam.KernelReg(
          endog=[Y],
          exog=[C1, C2, ovals],
          reg_type="ll",
          var_type="cco",
          bw=bw_cv_ls,
      )
      sm_mean, sm_mfx = model.fit()
      # TODO: add expected result
      sm_R2 = model.r_squared()  # noqa: F841
      npt.assert_allclose(sm_mfx[0, :], [b1, b2, b3], rtol=2e-1)
  
imports: import pytest
  import numpy
  import numpy.testing
  import statsmodels.api
label_desc: Use image node_id 5 for calling the TestKernelReg obj's underlying member method code with example usage: obj.test_mixed_mfx_ll_cvls(file_name) without return types