code: def load_data(location="/tmp/mnist"):
      (train_images, train_labels) = read_data_sets(location, "train")
      (test_images, test_labels) = read_data_sets(location, "test")
      X_train = normalizer(train_images, TRAIN_MEAN, TRAIN_STD)
      X_test = normalizer(test_images, TRAIN_MEAN, TRAIN_STD)
      Y_train = train_labels + 1
      Y_test = test_labels + 1
      return (X_train, Y_train), (X_test, Y_test)
  
file_path: BigDL/python/dllib/src/bigdl/dllib/feature/dataset/mnist.py
imports: import gzip
  import numpy
  from bigdl.dllib.feature.dataset import base
  from bigdl.dllib.feature.dataset.transformer import *
  from bigdl.dllib.utils.log4Error import *
label_desc: Use image node_id 5 for calling a global function with example usage: load_data(location) and returns: X_train,  Y_train,  X_test,  Y_test