code: def submit(nworker, nserver, fun_submit, hostIP="auto", pscmd=None):
      if nserver == 0:
          pscmd = None
  
      envs = {"DMLC_NUM_WORKER": nworker, "DMLC_NUM_SERVER": nserver}
      hostIP = get_host_ip(hostIP)
  
      if nserver == 0:
          rabit = RabitTracker(hostIP=hostIP, nslave=nworker)
          envs.update(rabit.slave_envs())
          rabit.start(nworker)
          if rabit.alive():
              fun_submit(nworker, nserver, envs)
      else:
          pserver = PSTracker(hostIP=hostIP, cmd=pscmd, envs=envs)
          envs.update(pserver.slave_envs())
          if pserver.alive():
              fun_submit(nworker, nserver, envs)
  
      if nserver == 0:
          rabit.join()
      else:
          pserver.join()
  
imports: from __future__ import absolute_import
  import os
  import sys
  import socket
  import struct
  import subprocess
  import argparse
  import time
  import logging
  from threading import Thread
label_desc: Use image node_id 4 for calling a global function with example usage: submit(nworker, nserver, fun_submit, hostIP, pscmd) without return types