code: def training_loop(self) -> None:
      pass
  
imports: import pytest
  import ray
  from ray.train import Checkpoint, CheckpointConfig, ScalingConfig
  from ray.air._internal.config import ensure_only_allowed_dataclass_keys_updated
  from ray.data.preprocessor import Preprocessor
  from ray.train.trainer import BaseTrainer
label_desc: Use image node_id 1 for calling the DummyTrainer obj's underlying member method code with example usage: obj.training_loop() without return types