code: def test_fwd_fwd_bwd_bwd():
      with temp_files_ctx(num=1) as temp_files:
          torch.multiprocessing.spawn(
              fn=main,
              nprocs=2,
              args=(temp_files[0],),
              join=True,
          )
  
file_path: fairscale/tests/nn/data_parallel/test_fsdp_fwd_fwd_bwd_bwd.py
imports: import torch
  import torch.nn
  from fairscale.fair_dev.testing.testing import skip_if_single_gpu, temp_files_ctx
  from fairscale.nn import enable_wrap, wrap
  from fairscale.nn.data_parallel import FullyShardedDataParallel
label_desc: Use image node_id 2 for calling a global function with example usage: test_fwd_fwd_bwd_bwd() without return types