code: def test_missing(self):
      np.random.seed(34234)
      time = 50 * np.random.uniform(size=200)
      status = np.random.randint(0, 2, 200).astype(np.float64)
      exog = np.random.normal(size=(200, 4))
  
      time[0:5] = np.nan
      status[5:10] = np.nan
      exog[10:15, :] = np.nan
  
      md = PHReg(time, exog, status, missing="drop")
      assert_allclose(len(md.endog), 185)
      assert_allclose(len(md.status), 185)
      assert_allclose(md.exog.shape, np.r_[185, 4])
  
imports: import itertools
  import os
  import numpy
  from statsmodels.duration.hazard_regression import PHReg
  from numpy.testing import assert_allclose, assert_equal, assert_
  import pandas
  import pytest
  from .results import survival_r_results
  from .results import survival_enet_r_results
label_desc: Use image node_id 3 for calling the TestPHReg obj's underlying member method code with example usage: obj.test_missing() without return types