code: def forward(self, x):
      x = self.l0(x)
      x = self.l1(x)
      x = self.l2(x)
      x = self.l3(x)
      return x
  
file_path: fairscale/tests/nn/data_parallel/test_fsdp_shared_weights.py
imports: from copy import deepcopy
  import pytest
  import torch
  import torch.multiprocessing
  from torch.nn import Linear, Module
  from torch.optim import SGD
  from fairscale.fair_dev.testing.testing import dist_init, objects_are_equal, skip_if_single_gpu, teardown, temp_files_ctx
  from fairscale.nn.data_parallel import FullyShardedDataParallel
label_desc: Use image node_id 2 for calling the Model obj's underlying member method code with example usage: obj.forward(x) and returns: x