code: def test_dtoh(self):
      def model(x, y):
          a = x + y
          b = a.cpu() * 3
          return b
  
      @torch._dynamo.optimize("cudagraphs")
      def fn(x, y):
          for i in range(N_ITERS):
              loss = model(x, y).sum()
              loss.backward()
  
      x = torch.randn(3, device="cuda", requires_grad=True)
      y = torch.randn(3, device="cuda")
      fn(x, y)
  
imports: import functools
  import unittest
  import torch
  import torch._dynamo
  import torch._dynamo.config
  import torch._dynamo.test_case
  import torch._dynamo.testing
  from torch._dynamo.testing import same
  from torch.testing._internal.common_utils import TEST_CUDA_GRAPH
label_desc: Use image node_id 2 for calling the TestAotCudagraphs obj's underlying member method code with example usage: obj.test_dtoh() and returns: b