code: def unsupervised_training_step(self, batch, *args):
      self.unlabeled_data.extend(batch)
      return {"loss": torch.tensor(0.0, requires_grad=True)}
  
imports: import unittest
  from argparse import Namespace
  import torch
  from baal.active import ActiveLearningDataset
  from pytorch_lightning import Trainer
  from baal.utils.ssl_module import SSLModule
  from torch import nn
  from torch.utils.data import ConcatDataset
  from tests.utils.ssl_iterator_test import SSLTestDataset
label_desc: Use image node_id 4 for calling the TestSSLModule obj's underlying member method code with example usage: obj.unsupervised_training_step(batch) and returns: dict