code: def check_dataset_exist(dirpath):
      if not os.path.exists(dirpath):
          print(
              "Please download the cifar10 dataset using python data/download_cifar10.py"
          )
          sys.exit(0)
      return dirpath
  
file_path: singa/examples/cifar_distributed_cnn/data/cifar10.py
imports: import numpy
  import os
  import sys
label_desc: Use image node_id 4 for calling a global function with example usage: check_dataset_exist(dirpath) and returns: dirpath