code: def forward(self, x):
      return self.bn(self.fc(x))
  
imports: import copy
  import math
  import unittest
  import unittest.mock
  import torch
  import torch.nn
  from classy_vision.hooks import ExponentialMovingAverageModelHook
  from classy_vision.models import ClassyModel
  from test.generic.hook_test_utils import HookTestBase
label_desc: Use image node_id 4 for calling the TestModel obj's underlying member method code with example usage: obj.forward(x) and returns: self