class_docstr: Step a single env in a separate process for lock free paralellism.
class_docstr_tok: ["Step","a","single","env","in","a","separate","process","for","lock","free","paralellism","."]
code: def observation_spec(self) -> types.NestedArraySpec:
      if not self._observation_spec:
          self._observation_spec = self.call("observation_spec")()
      return self._observation_spec
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import atexit
  import sys
  import traceback
  from typing import Any, Callable, Sequence, Text, Union
  from absl import logging
  import cloudpickle
  import gin
  import numpy
  import tensorflow
  from tf_agents.environments import py_environment
  from tf_agents.system import system_multiprocessing
  from tf_agents.trajectories import time_step
  from tf_agents.typing import types
  from tf_agents.utils import nest_utils
label_desc: Use image node_id 4 for calling the ProcessPyEnvironment obj's underlying member method code with example usage: obj.observation_spec() and returns: self