code: def all_survival_function_estimators():
      estimators = set()
      for cls in all_survival_estimators():
          if hasattr(cls, "predict_survival_function"):
              if issubclass(cls, CoxnetSurvivalAnalysis):
                  est = cls(fit_baseline_model=True)
              else:
                  est = cls()
              estimators.add(est)
      return estimators
  
file_path: scikit-survival/tests/test_survival_function.py
imports: import numpy
  from numpy.testing import assert_array_almost_equal
  import pytest
  from sksurv.linear_model import CoxnetSurvivalAnalysis
  from sksurv.testing import all_survival_estimators
  from sksurv.util import Surv
label_desc: Use image node_id 1 for calling a global function with example usage: all_survival_function_estimators() and returns: estimators