code: def test_get_synthetic_summary_holdout():
      summary = get_synthetic_summary_holdout(
          synthetic_data_func=simulate_nuisance_and_easy_treatment
      )
  
      print(summary)
  
file_path: causalml/tests/test_datasets.py
imports: import pytest
  from causalml.dataset import simulate_nuisance_and_easy_treatment, simulate_hidden_confounder, simulate_randomized_trial
  from causalml.dataset import get_synthetic_preds, get_synthetic_summary, get_synthetic_auuc
  from causalml.dataset import get_synthetic_preds_holdout, get_synthetic_summary_holdout
  from causalml.inference.meta import LRSRegressor, XGBTRegressor
label_desc: Use image node_id 4 for calling a global function with example usage: test_get_synthetic_summary_holdout() without return types