code: def test_copy_loss_forward_shape(self):
      for params, init_case in itertools.product(
          self.PARAMS, self.INIT_CASES
      ):
          loss = CopyGeneratorLoss(**init_case)
          dummy_in = self.dummy_inputs(params, init_case)
          res = loss(*dummy_in)
          expected_shape = self.expected_shape(params, init_case)
          self.assertEqual(
              res.shape, expected_shape, init_case.__str__()
          )
  
imports: import unittest
  from onmt.modules.copy_generator import CopyGenerator, CopyGeneratorLoss
  import itertools
  from copy import deepcopy
  import torch
  from torch.nn.functional import softmax
  from onmt.tests.utils_for_tests import product_dict
label_desc: Use image node_id 3 for calling the TestCopyGeneratorLoss obj's underlying member method code with example usage: obj.test_copy_loss_forward_shape() without return types