class_docstr: Test the PipelineHelper class.
class_docstr_tok: ["Test","the","PipelineHelper","class","."]
code: def test_join_tensor(self):
      t = torch.randn(8, 5)
      j = PipelineHelper.join([t, t, t, t])
      assert isinstance(j, torch.Tensor)
      assert j.shape == (32, 5)
  
      j = PipelineHelper.join([t, t], dim=1)
      assert isinstance(j, torch.Tensor)
      assert j.shape == (8, 10)
  
imports: import torch
  import numpy
  import unittest
  from parlai.utils.torch import padded_tensor, argsort, PipelineHelper, neginf, IdentityLayer, trainable_parameters, total_parameters
label_desc: Use image node_id 8 for calling the TestPipelineHelper obj's underlying member method code with example usage: obj.test_join_tensor() without return types