code: def test_fallback(self) -> None:
      with patch.dict(optimizer_argparse.funcs, {}):
  
          @optimizer_argparse.register(AcquisitionFunction)
          # pyre-fixme[3]: Return type must be annotated.
          def _argparse(acqf: MaybeType[DummyAcquisitionFunction]):
              pass
  
          self.assertEqual(
              optimizer_argparse[DummyAcquisitionFunction], _argparse
          )
  
imports: from __future__ import annotations
  from importlib import reload
  from unittest.mock import patch
  from ax.models.torch.botorch_modular import optimizer_argparse
  from ax.models.torch.botorch_modular.optimizer_argparse import _argparse_base, MaybeType, optimizer_argparse
  from ax.utils.common.constants import Keys
  from ax.utils.common.testutils import TestCase
  from botorch.acquisition.acquisition import AcquisitionFunction
  from botorch.acquisition.knowledge_gradient import qKnowledgeGradient, qMultiFidelityKnowledgeGradient
  from botorch.acquisition.max_value_entropy_search import qMaxValueEntropy, qMultiFidelityMaxValueEntropy
  from botorch.acquisition.multi_objective.monte_carlo import qExpectedHypervolumeImprovement, qNoisyExpectedHypervolumeImprovement
label_desc: Use image node_id 3 for calling the OptimizerArgparseTest obj's underlying member method code with example usage: obj.test_fallback() without return types