code: def test_pop_not_stashed():
      @skippable(pop=["foo"])
      class Pop(nn.Module):
          def forward(self, input):
              yield pop("foo")
  
      l1 = Pop()
  
      with pytest.raises(RuntimeError):
          l1(torch.tensor(42))
  
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 7 for calling a global function with example usage: test_pop_not_stashed() without return types