code: def tearDown(self):
      registry.unregister("clevr_text_vocab_size")
      registry.unregister("clevr_num_final_outputs")
      registry.unregister("config")
      del self.config
      gc.collect()
  
file_path: mmf/tests/models/test_cnn_lstm.py
imports: import gc
  import os
  import unittest
  import numpy
  import torch
  from mmf.common.registry import registry
  from mmf.common.sample import Sample, SampleList
  from mmf.models.cnn_lstm import CNNLSTM
  from mmf.utils.configuration import Configuration
  from mmf.utils.general import get_current_device, get_mmf_root
  from tests.test_utils import dummy_args
label_desc: Use image node_id 2 for calling the TestModelCNNLSTM obj's underlying member method code with example usage: obj.tearDown() without return types