code: def init_comm(backend, gpus):
      """Init communication backend
  
      Parameters
      ----------
      backend
          The communication backend
      gpus
  
  
      Returns
      -------
      store
          The kvstore
      num_workers
          The total number of workers
      rank
      local_rank
      is_master_node
      ctx_l
      """
      # backend specific implementation
      import mxnet as mx
  
      if backend == "horovod":
          try:
              import horovod.mxnet as hvd  # pylint: disable=import-outside-toplevel
          except ImportError:
              logging.info("horovod must be installed.")
              sys.exit(1)
          hvd.init()
          store = None
          num_workers = hvd.size()
          rank = hvd.rank()
          local_rank = hvd.local_rank()
          is_master_node = rank == local_rank
          ctx_l = [mx.gpu(local_rank)]
          logging.info("GPU communication supported by horovod")
      else:
          store = mx.kv.create(backend)
          num_workers = store.num_workers
          rank = store.rank
          local_rank = 0
          is_master_node = rank == local_rank
          if gpus == "-1" or gpus == "":
              ctx_l = [mx.cpu()]
              logging.info("Runing on CPU")
          else:
              ctx_l = [mx.gpu(int(x)) for x in gpus.split(",")]
              logging.info("GPU communication supported by KVStore")
  
      return store, num_workers, rank, local_rank, is_master_node, ctx_l
  
imports: import argparse
  import os
  import sys
  import inspect
  import logging
  import warnings
  import functools
  import uuid
  from types import ModuleType
  from typing import Optional
  import numpy
  import hashlib
  import requests
  import itertools
  import random
  from .lazy_imports import try_import_boto3
  from mxnet.gluon.utils import replace_file
  import glob
label_desc: Use image node_id 16 for calling a global function with example usage: init_comm(backend, gpus) and returns: store,  num_workers,  rank,  local_rank,  is_master_node,  ctx_l