code: def setUp(self):
      self.lightning_losses = []
      self.mmf_losses = []
  
file_path: mmf/tests/trainers/lightning/test_loss.py
imports: import unittest
  from unittest.mock import MagicMock, patch
  from mmf.common.report import Report
  from pytorch_lightning.callbacks.base import Callback
  from tests.trainers.test_utils import get_config_with_defaults, get_lightning_trainer, get_mmf_trainer
label_desc: Use image node_id 1 for calling the TestLightningTrainerLoss obj's underlying member method code with example usage: obj.setUp() without return types