code: def test_load_lymphoma_logrank():
      # from https://www.statsdirect.com/help/content/survival_analysis/logrank.htm
      df_ = load_lymphoma()
      results = stats.multivariate_logrank_test(
          df_["Time"], df_["Stage_group"], df_["Censor"]
      )
      assert abs(results.test_statistic - 6.70971) < 1e-4
      assert abs(results.p_value - 0.0096) < 1e-4
  
imports: import numpy
  import pandas
  import numpy.testing
  import pytest
  from pandas.testing import assert_frame_equal
  from lifelines import statistics
  from lifelines import CoxPHFitter, KaplanMeierFitter, WeibullFitter
  from lifelines.exceptions import StatisticalWarning
  from lifelines.datasets import load_waltons, load_g3, load_lymphoma, load_dd, load_regression_dataset, load_leukemia
label_desc: Use image node_id 8 for calling a global function with example usage: test_load_lymphoma_logrank() without return types