code: def test_dataset(backend_default, data):
      dataset = MNIST(path=data)
      dataset.gen_iterators()
      train_set = dataset.data_dict["train"]
      train_set.be = NervanaObject.be
  
      for i in range(2):
          for X_batch, y_batch in train_set:
              neon_logger.display(
                  "Xshape: {}, yshape: {}".format(
                      X_batch.shape, y_batch.shape
                  )
              )
          train_set.index = 0
  
file_path: neon/tests/test_dataset.py
imports: import numpy
  import os
  from neon import NervanaObject
  from neon import logger
  from neon.data import MNIST
  from neon.data.text import Text
label_desc: Use image node_id 1 for calling a global function with example usage: test_dataset(backend_default, data) without return types