code: def _pre_processing(self, x, validation_data=None):
      long_term, short_term = self._reshape_input_x(x)
      if validation_data:
          val_x, val_y = validation_data
          long_val, short_val = self._reshape_input_x(val_x)
          validation_data = ([long_val, short_val], val_y)
      return [long_term, short_term], validation_data
  
imports: import pickle
  import numpy
  import time
  from tensorflow.keras.models import Model
  from tensorflow.keras.layers import *
  from tensorflow.keras.initializers import TruncatedNormal, Constant
  import tensorflow.keras.backend
  import tensorflow
  from bigdl.orca.automl.metrics import Evaluator
  from bigdl.orca.automl.model.abstract import BaseModel
label_desc: Use image node_id 7 for calling the MTNetKeras obj's underlying member method code with example usage: obj._pre_processing(x, validation_data) and returns: list,  validation_data