code: def main():
      parser = argparse.ArgumentParser(
          description="Launch a distributed training job for BytePS"
      )
      parser.add_argument(
          "-WH",
          "--worker-hostfile",
          required=True,
          type=str,
          help="the hostfile of worker machines which will run the job.",
      )
      parser.add_argument(
          "-SH",
          "--server-hostfile",
          required=True,
          type=str,
          help="the hostfile of server machines which will run the job.",
      )
      parser.add_argument(
          "--scheduler-ip",
          required=True,
          type=str,
          help="the ip address of the scheduler",
      )
      parser.add_argument(
          "--scheduler-port",
          required=True,
          type=int,
          help="the port of the scheduler",
      )
      parser.add_argument(
          "--interface",
          type=str,
          default="eth0",
          help="the network interface to use",
      )
      parser.add_argument(
          "--env",
          action="append",
          default=[],
          help="Given a pair of environment_variable:value, sets this value of \
                          environment variable for all workers and servers. Example OMP_NUM_THREADS:3",
      )
      parser.add_argument(
          "--username", type=str, help="the username for ssh"
      )
      parser.add_argument(
          "--scheduler-ssh-port",
          type=str,
          default="22",
          help="the ssh port of the scheduler",
      )
      parser.add_argument(
          "command", nargs="+", help="command for launching the program"
      )
  
      args = parser.parse_args()
  
      # check necessary args
      assert args.worker_hostfile
      assert args.server_hostfile
      assert args.scheduler_ip
      assert args.scheduler_port
  
      submit(args)
  
file_path: byteps/launcher/dist_launcher.py
imports: import argparse
  import os, sys
  import signal
  import logging
  import subprocess
  from multiprocessing import Pool, Process
  from threading import Thread
label_desc: Use image node_id 6 for calling a global function with example usage: main() without return types