code: def test_experimental_warning() -> None:
      with pytest.warns(optuna.exceptions.ExperimentalWarning):
          optuna.samplers.QMCSampler()
  
imports: from typing import Any
  from typing import Callable
  from typing import Dict
  from unittest.mock import Mock
  from unittest.mock import patch
  import warnings
  import numpy
  import pytest
  import optuna
  from optuna.distributions import BaseDistribution
  from optuna.trial import Trial
  from optuna.trial import TrialState
label_desc: Use image node_id 2 for calling a global function with example usage: test_experimental_warning() without return types