code: def test_sample_independent() -> None:
      sampler = MOTPEMultiObjectiveSampler()
      study = optuna.multi_objective.create_study(
          directions=["minimize", "maximize"], sampler=sampler
      )
  
      def _objective(
          trial: multi_objective.trial.MultiObjectiveTrial,
      ) -> Tuple[float, float]:
          x = trial.suggest_float("x", 0, 1)
          y = trial.suggest_float("y", 0, 1)
          return x, y
  
      with patch.object(
          MOTPESampler,
          "sample_independent",
          wraps=sampler._motpe_sampler.sample_independent,
      ) as mock:
          study.optimize(_objective, n_trials=10)
          assert mock.call_count == 20
  
file_path: optuna/tests/multi_objective_tests/samplers_tests/test_motpe.py
imports: from typing import Dict
  from typing import Tuple
  from unittest.mock import Mock
  from unittest.mock import patch
  import pytest
  import optuna
  from optuna import multi_objective
  from optuna.multi_objective.samplers import MOTPEMultiObjectiveSampler
  from optuna.samplers import MOTPESampler
label_desc: Use image node_id 4 for calling a global function with example usage: test_sample_independent() and returns: x,  y