docstr: Override fit status to test full transform_batch path.
code: def fit_status(self) -> Preprocessor.FitStatus:
      """Override fit status to test full transform_batch path."""
      return Preprocessor.FitStatus.FITTED
  
imports: import uuid
  from typing import Dict, Optional, Union
  from unittest import mock
  import numpy
  import pandas
  import pytest
  import ray
  from ray.air.constants import TENSOR_COLUMN_NAME
  from ray.air.util.data_batch_conversion import BatchFormat
  from ray.data import Preprocessor
  from ray.train._internal.framework_checkpoint import FrameworkCheckpoint
  from ray.train.predictor import Predictor, PredictorNotSerializableException
  from ray.train.tests.util import create_dict_checkpoint, load_dict_checkpoint
label_desc: Use image node_id 2 for calling the DummyPreprocessor obj's underlying member method code with example usage: obj.fit_status() and returns: Preprocessor