code: def transform_batch(self, batch):
      self._batch_transformed = True
      return self.transform(batch)
  
file_path: ray/python/ray/train/tests/dummy_preprocessor.py
imports: import uuid
  from ray.data.preprocessor import Preprocessor
label_desc: Use image node_id 2 for calling the DummyPreprocessor obj's underlying member method code with example usage: obj.transform_batch(batch) and returns: self