code: def step(self, gradients: List[Optional[Tensor]]):
      # call the custom optimizer step implementation
      with torch.no_grad():
          raise RuntimeError(
              "MyDummyFnOptimizer does not support step() as of now"
          )
  
imports: from typing import List, Optional, Tuple
  import unittest
  import torch
  import torch.distributed
  import torch.nn
  import torch.nn.functional
  from torch import Tensor
  from torch.optim import SGD, Adam, AdamW
  from torch.testing._internal.common_utils import TestCase, run_tests
label_desc: Use image node_id 3 for calling the MyDummyFnOptimizer obj's underlying member method code with example usage: obj.step(gradients) without return types