class_docstr: Describe the environment inside which the job is running.
  This includes job id, number of GPUs available, ...
  
  This class can only be instantiated from a running submitit job.
  
  @plugin-dev: default implementation look for information into environment variables.
  Override _env to map environment variable to each property.
code: def array_task_id(self) -> tp.Optional[str]:
      n = "array_task_id"
      return (
          None
          if n not in self._env
          else os.environ.get(self._env[n], None)
      )
  
imports: import os
  import signal
  import socket
  import sys
  import time
  import types
  import typing
  from pathlib import Path
  from .None import logger, utils
  from .utils import DelayedSubmission, JobPaths
label_desc: Use image node_id 11 for calling the JobEnvironment obj's underlying member method code with example usage: obj.array_task_id() and returns: unknown