docstr: Check that the ``step()`` method (without closure) is handled as
  expected.
docstr_tok: ["Check","that","the","``","step","(",")","``","method","(","without","closure",")","is","handled","as","expected","."]
code: def test_step_without_closure(self):
      """Check that the ``step()`` method (without closure) is handled as
      expected."""
      self.dist_init(self.rank)
      LR = 0.1
  
      class SGDWithoutClosure(torch.optim.SGD):
          def step(self):
              return super().step()
  
      x = torch.tensor([1.0], device=self.device, requires_grad=True)
      o = ZeroRedundancyOptimizer(
          [x],
          optimizer_class=SGDWithoutClosure,
          lr=LR,
      )
      x.backward()
      o.step()
      self.assertEqual(x, torch.tensor([0.9], device=self.device))
  
imports: import copy
  import os
  import sys
  import unittest
  from contextlib import nullcontext
  from typing import Any, cast, List
  import numpy
  import torch
  import torch.distributed
  from torch.distributed.algorithms.ddp_comm_hooks.ddp_zero_hook import hook_with_zero_step, hook_with_zero_step_interleaved
  from torch.distributed.algorithms.ddp_comm_hooks.default_hooks import allreduce_hook
  from torch.distributed.algorithms.join import Join, Joinable, JoinHook
  from torch.distributed.optim import ZeroRedundancyOptimizer
  from torch.distributed.optim.zero_redundancy_optimizer import _broadcast_object
  from torch.nn.parallel import DistributedDataParallel
  from torch.optim import AdamW, SGD
  from torch.testing._internal import common_distributed
  from torch.testing._internal.common_utils import instantiate_parametrized_tests, IS_WINDOWS, parametrize, run_tests, TEST_WITH_ASAN, TEST_WITH_DEV_DBG_ASAN
label_desc: Use image node_id 5 for calling the TestZeroRedundancyOptimizerSingleRank obj's underlying member method code with example usage: obj.test_step_without_closure() and returns: super