code: def test_ties(rossi):
      cph = CoxPHSurvivalAnalysis(ties="xyz")
  
      msg = r"The 'ties' parameter of CoxPHSurvivalAnalysis must be a str among {.+}\. Got 'xyz' instead\."
  
      with pytest.raises(ValueError, match=msg):
          cph.fit(rossi.x.values, rossi.y)
  
imports: import warnings
  import numpy
  from numpy.testing import assert_array_almost_equal
  import pandas
  import pytest
  from scipy.optimize import check_grad
  from sklearn.exceptions import ConvergenceWarning
  from sklearn.pipeline import make_pipeline
  from sklearn.preprocessing import StandardScaler
  from sksurv.column import standardize
  from sksurv.datasets import load_breast_cancer
  from sksurv.linear_model.coxph import CoxPHOptimizer, CoxPHSurvivalAnalysis
  from sksurv.preprocessing import OneHotEncoder
label_desc: Use image node_id 13 for calling the TestCoxPH obj's underlying member method code with example usage: obj.test_ties(rossi) without return types