code: def test_stash(skip_tracker):
      @skippable(stash=["foo"])
      class Stash(nn.Module):
          def forward(self, input):
              yield stash("foo", input)
              return input * 2
  
      l1 = Stash()
  
      assert len(skip_tracker.tensors) == 0
  
      with use_skip_tracker(skip_tracker):
          l1(torch.tensor(42))
  
      assert len(skip_tracker.tensors) == 1
  
file_path: fairscale/tests/nn/pipe/skip/test_stash_pop.py
imports: import pytest
  import torch
  from torch import nn
  from fairscale.nn.pipe.skip import pop, skippable, stash
  from fairscale.nn.pipe.skip.tracker import SkipTracker, use_skip_tracker
label_desc: Use image node_id 2 for calling a global function with example usage: test_stash(skip_tracker) and returns: unknown