code: def fetch_defense_data(self):
      
      if self.defenses_data_initialized:
        return
      logging.info('Fetching defense data from datastore')
      # init data from datastore
      self.submissions.init_from_datastore()
      self.dataset_batches.init_from_datastore()
      self.adv_batches.init_from_datastore()
      # read dataset metadata
      self.read_dataset_metadata()
      # mark as initialized
      self.defenses_data_initialized = True
docs: Lazy initialization of data necessary to execute defenses.