code: def slurm_distributed_context(opt):
      """
      Initialize a distributed context, using the SLURM environment.
  
      Does some work to read the environment to find a list of participating nodes
      and the main node.
  
      :param opt:
          Command line options.
      """
      # We can determine the init method automatically for Slurm.
      # double check we're using SLURM
      node_list = os.environ.get("SLURM_JOB_NODELIST")
      if node_list is None:
          raise RuntimeError(
              "Does not appear to be in a SLURM environment. "
              "You should not call this script directly; see launch_distributed.py"
          )
      try:
          # Figure out the main host, and which rank we are.
          hostnames = subprocess.check_output(
              ["scontrol", "show", "hostnames", node_list]
          )
      except FileNotFoundError as e:
          # Slurm is not installed
          raise RuntimeError(
              f"SLURM does not appear to be installed. Missing file: {e.filename}"
          )
  
      main_host = hostnames.split()[0].decode("utf-8")
      distributed_rank = int(os.environ["SLURM_PROCID"])
      if opt.get("model_parallel"):
          # -1 signals to multiprocessing_train to use all GPUs available.
          # (A value of None signals to multiprocessing_train to use the GPU
          # corresponding to the rank.
          device_id = -1
      else:
          device_id = int(os.environ["SLURM_LOCALID"])
      port = opt["port"]
      logging.info(
          f"Initializing host {socket.gethostname()} as rank {distributed_rank}, "
          f"main is {main_host}"
      )
      # Begin distributed training
      with distributed_context(
          distributed_rank,
          opt,
          0,
          device_id,
          init_method=f"tcp://{main_host}:{port}",
      ) as opt:
          yield opt
  
file_path: ParlAI/parlai/utils/distributed.py
imports: import builtins
  import copy
  import os
  import pickle
  import contextlib
  import subprocess
  import socket
  import parlai.utils.logging
label_desc: Use image node_id 11 for calling a global function with example usage: slurm_distributed_context(opt) without return types