class_docstr: An error happened from main process.
class_docstr_tok: ["An","error","happened","from","main","process","."]
docstr: Return a custom error message.
docstr_tok: ["Return","a","custom","error","message","."]
code: def __str__(self):
      """Return a custom error message."""
      return self._msg
  
file_path: espnet/espnet/distributed/pytorch_backend/launch.py
imports: import multiprocessing
  import os
  import signal
  import socket
  import time
label_desc: Use image node_id 2 for calling the MainProcessError obj's underlying member method code with example usage: obj.__str__() and returns: self