code: def test_non_tensor():
      class NonTensor(nn.Module):
          def forward(self, _):
              return "hello"
  
      model = nn.Sequential(NonTensor())
      model = Pipe(model, balance=[1], devices=["cpu"])
      x = torch.rand(1)
  
      # TypeError: expected Tensor as element 0 in argument 0, but got str
      with pytest.raises(TypeError):
          model(x)
  
      # TypeError: expected Tensor to scatter, but got str
      with pytest.raises(TypeError):
          model("hello")
  
imports: from collections import OrderedDict
  from copy import deepcopy
  import time
  import pytest
  import torch
  from torch import nn
  from fairscale.nn.pipe import Pipe
label_desc: Use image node_id 21 for calling a global function with example usage: test_non_tensor() and returns: str