code: def map_transform(self, data: DataEntry, is_train: bool) -> DataEntry:
      length = target_transformation_length(
          data[self.target_field], self.ext_length, is_train
      )
      data[self.field] = np.broadcast_to(
          data[self.field],
          (data[self.field].shape[:-1] + (length,)),
      )
      return data
  
file_path: gluonts/src/gluonts/mx/model/tft/_transform.py
imports: import numpy
  from gluonts.core.component import validated
  from gluonts.dataset.common import DataEntry
  from gluonts.dataset.field_names import FieldName
  from gluonts.transform import MapTransformation, target_transformation_length
label_desc: Use image node_id 2 for calling the BroadcastTo obj's underlying member method code with example usage: obj.map_transform(data, is_train) and returns: data