code: def wait(self, timeout=None):
      if self.returncode is None:
          if timeout is not None:
              if not wait([self.sentinel], timeout):
                  return None
          # This shouldn't block if wait() returned successfully.
          return self.poll(os.WNOHANG if timeout == 0.0 else 0)
      return self.returncode
  
file_path: catboost/contrib/python/joblib/joblib/externals/loky/backend/popen_loky_posix.py
imports: import os
  import sys
  import signal
  import pickle
  from io import BytesIO
  from multiprocessing import util, process
  from multiprocessing.connection import wait
  from multiprocessing.context import set_spawning_popen
  from .None import reduction, resource_tracker, spawn
label_desc: Use image node_id 4 for calling the Popen obj's underlying member method code with example usage: obj.wait(timeout) and returns: self, self, None