code: def test_concordance_index_will_not_overflow():
      a = np.arange(65536)
      assert concordance_index(a, a) == 1.0
      b = np.arange(65537)
      assert concordance_index(b, b) == 1.0
      assert concordance_index(b, b[::-1]) == 0.0
  
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 5 for calling a global function with example usage: test_concordance_index_will_not_overflow() without return types