code: def get_train_data_iter(config, kv):
      from mxnet.test_utils import get_mnist_iterator
      from filelock import FileLock
  
      with FileLock("data.lock"):
          iters = get_mnist_iterator(
              config["batch_size"],
              (1, 28, 28),
              num_parts=kv.num_workers,
              part_index=kv.rank,
          )
          return iters[0]
  
file_path: BigDL/python/orca/example/learn/mxnet/lenet_mnist.py
imports: import argparse
  from bigdl.orca import init_orca_context, stop_orca_context
  from bigdl.orca.learn.mxnet import Estimator, create_config
label_desc: Use image node_id 1 for calling a global function with example usage: get_train_data_iter(config, kv) and returns: iters