class_docstr: propagate exceptions to the parent's thread
  refer to https://stackoverflow.com/a/31614591/9601110
class_docstr_tok: ["propagate","exceptions","to","the","parent","'s","thread","refer","to","https",":","\/\/stackoverflow.com\/a\/31614591\/9601110"]
code: def run(self):
      self.exc = None
      try:
          if hasattr(self, "_Thread__target"):
              #  python 2.x
              self.ret = self._Thread__target(
                  *self._Thread__args, **self._Thread__kwargs
              )
          else:
              # python 3.x
              self.ret = self._target(*self._args, **self._kwargs)
      except BaseException as e:
          self.exc = e
      if self.callback is not None:
          self.callback(self.idx)
  
file_path: byteps/launcher/launch.py
imports: from __future__ import print_function
  import os
  import re
  import subprocess
  import threading
  import sys
  import time
  from functools import reduce
label_desc: Use image node_id 2 for calling the PropagatingThread obj's underlying member method code with example usage: obj.run() without return types