code: def test_both_concordance_index_with_only_censoring_fails_gracefully():
      actual_times = np.array([1, 2, 3])
      predicted_times = np.array([1, 2, 3])
      obs = np.zeros(3)
      with pytest.raises(ZeroDivisionError, match="admissable pairs"):
          fast_cindex(actual_times, predicted_times, obs)
  
      with pytest.raises(ZeroDivisionError, match="admissable pairs"):
          slow_cindex(actual_times, predicted_times, obs)
  
file_path: lifelines/lifelines/tests/utils/test_concordance.py
imports: import pytest
  import numpy
  import pandas
  from lifelines import CoxPHFitter
  from lifelines.datasets import load_rossi
  from lifelines.utils.concordance import concordance_index
  from lifelines.utils.concordance import concordance_index
  from lifelines.utils.concordance import naive_concordance_index
label_desc: Use image node_id 3 for calling a global function with example usage: test_both_concordance_index_with_only_censoring_fails_gracefully() without return types