code: def with_strata(rossi):
      check_cox(
          rossi,
          x=["age", "fin", "race", "wexp", "mar", "paro", "prio"],
          stratify_by=["race", "mar"],
          formula="Surv(week, arrest) ~ fin + age + wexp + paro + prio + strata(race) + strata(mar)",
      )
  
file_path: h2o-3/h2o-py/tests/testdir_algos/coxph/pyunit_coxph_concordance_survival.py
imports: import sys
  import h2o
  from lifelines import CoxPHFitter
  from lifelines.datasets import load_rossi
  from pandas.testing import assert_frame_equal
  from tests import pyunit_utils
  from h2o.estimators.coxph import H2OCoxProportionalHazardsEstimator
label_desc: Use image node_id 3 for calling a global function with example usage: with_strata(rossi) without return types