code: def test_fp16_works(self):
      trainer = MMFTrainerMock(100, 2, 0.04)
      trainer.load_datasets()
      trainer.load_fp16_scaler()
      self.assertTrue(
          isinstance(trainer.scaler, torch.cuda.amp.GradScaler)
      )
      self.assertEqual(trainer.current_iteration, 0)
      trainer.training_loop()
      self.assertEqual(trainer.current_iteration, 4)
  
file_path: mmf/tests/trainers/test_fp16.py
imports: import unittest
  import torch
  from tests.test_utils import SimpleModel, skip_if_no_cuda
  from tests.trainers.test_training_loop import TrainerTrainingLoopMock
  from tests.trainers.test_utils import get_config_with_defaults
label_desc: Use image node_id 1 for calling the TestFp16 obj's underlying member method code with example usage: obj.test_fp16_works() without return types