code: def create_transformation(self) -> Transformation:
      return Chain(
          [
              RemoveFields(
                  field_names=[
                      FieldName.FEAT_STATIC_REAL,
                      FieldName.FEAT_DYNAMIC_REAL,
                      FieldName.FEAT_DYNAMIC_CAT,
                  ]
              ),
              AddObservedValuesIndicator(
                  target_field=FieldName.TARGET,
                  output_field=FieldName.OBSERVED_VALUES,
                  dtype=self.dtype,
              ),
          ]
      )
  
file_path: gluonts/src/gluonts/nursery/robust-mts-attack/pts/model/n_beats/n_beats_estimator.py
imports: from typing import List, Optional
  import torch
  import torch.nn
  from gluonts.core.component import validated
  from gluonts.dataset.field_names import FieldName
  from gluonts.model.predictor import Predictor
  from gluonts.torch.model.predictor import PyTorchPredictor
  from gluonts.torch.util import copy_parameters
  from gluonts.transform import InstanceSplitter, ValidationSplitSampler, TestSplitSampler, AddObservedValuesIndicator, Transformation, Chain, RemoveFields, ExpectedNumInstanceSampler
  from pts import Trainer
  from pts.model import PyTorchEstimator
  from pts.model.utils import get_module_forward_input_names
  from .n_beats_network import NBEATSPredictionNetwork, NBEATSTrainingNetwork, VALID_N_BEATS_STACK_TYPES
label_desc: Use image node_id 3 for calling the NBEATSEstimator obj's underlying member method code with example usage: obj.create_transformation() and returns: Chain