code: def dummy_inputs(cls, params, init_case):
      hidden = torch.randn(
          (
              params["batch_size"] * params["tgt_max_len"],
              init_case["input_size"],
          )
      )
      attn = torch.randn(
          (
              params["batch_size"] * params["tgt_max_len"],
              params["max_seq_len"],
          )
      )
      src_map = torch.randn(
          (
              params["batch_size"],
              params["max_seq_len"],
              params["n_extra_words"],
          )
      )
      return hidden, attn, src_map
  
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 1 for calling the TestCopyGenerator obj's underlying member method code with example usage: obj.dummy_inputs(cls, params, init_case) and returns: hidden,  attn,  src_map