code: def start_ssh(prog, node, port, username, fname):
      def run(prog):
          subprocess.check_call(prog, shell=True)
  
      dirname = "sshlog"
      if not os.path.exists(dirname):
          os.mkdir(dirname)
  
      pname = dirname + "/" + fname
      if username is not None:
          prog = (
              "ssh -o StrictHostKeyChecking=no "
              + " -l "
              + username
              + " "
              + node
              + " -p "
              + port
              + " '"
              + prog
              + "'"
              + " > "
              + pname
              + ".stdout"
              + " 2>"
              + pname
              + ".stderr&"
          )
      else:
          prog = (
              "ssh -o StrictHostKeyChecking=no "
              + node
              + " -p "
              + port
              + " '"
              + prog
              + "'"
              + " > "
              + pname
              + ".stdout"
              + " 2>"
              + pname
              + ".stderr&"
          )
  
      thread = Thread(target=run, args=(prog,))
      thread.setDaemon(True)
      thread.start()
      return thread
  
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 4 for calling a global function with example usage: start_ssh(prog, node, port, username, fname) and returns: thread