code: def _run_training_loop_and_validate(self, inp, models, optimizers):
      for i in range(6):
          for model in models:
              model(inp).sum().backward()
          for opt in optimizers:
              opt.step()
  
          with self.subTest(i):
              _validate_params(
                  [model.parameters() for model in models],
                  torch.testing.assert_allclose,
              )
  
          for opt in optimizers:
              opt.zero_grad(set_to_none=True)
  
file_path: pytorch/test/distributed/optim/test_apply_optimizer_in_backward.py
imports: import unittest
  from copy import deepcopy
  import torch
  import torch.nn
  from torch.distributed.optim import _apply_optimizer_in_backward, _get_in_backward_optimizers
label_desc: Use image node_id 1 for calling the ApplyOverlappedOptimizerTest obj's underlying member method code with example usage: obj._run_training_loop_and_validate(inp, models, optimizers) without return types