docs: def _create_warm_start_tuner(self, additional_parents, warm_start_type, estimator=None):
          """Creates a new ``HyperparameterTuner`` with ``WarmStartConfig``, where type will be equal to
          ``warm_start_type`` and``parents`` would be equal to union of ``additional_parents`` and self.
  
          Args:
              additional_parents (set{str}): Additional parents along with self, to be used for warm starting.
              warm_start_type (sagemaker.tuner.WarmStartTypes): Type of warm start job.
  
          Returns:
              sagemaker.tuner.HyperparameterTuner: Instance with the request fields copied from self along with the
              warm start configuration
          """
          all_parents = {self.latest_tuning_job.name}
          if additional_parents:
              all_parents = all_parents.union(additional_parents)
  
          return HyperparameterTuner(estimator=estimator if estimator else self.estimator,
                                     objective_metric_name=self.objective_metric_name,
                                     hyperparameter_ranges=self._hyperparameter_ranges,
                                     objective_type=self.objective_type,
                                     max_jobs=self.max_jobs,
                                     max_parallel_jobs=self.max_parallel_jobs,
                                     warm_start_config=WarmStartConfig(warm_start_type=warm_start_type,
                                                                       parents=all_parents))