code: def expected_shape(cls, params, init_case):
      return (params["batch_size"] * params["tgt_max_len"],)
  
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 2 for calling the TestCopyGeneratorLoss obj's underlying member method code with example usage: obj.expected_shape(cls, params, init_case) and returns: unknown