class_docstr: Fake actor which generates random actions and validates specs.
class_docstr_tok: ["Fake","actor","which","generates","random","actions","and","validates","specs","."]
code: def observe_first(self, timestep: dm_env.TimeStep):
      _validate_spec(self._spec.observations, timestep.observation)
  
imports: import threading
  from typing import List, Mapping, Optional, Sequence, Callable, Iterator
  from acme import core
  from acme import specs
  from acme import types
  from acme import wrappers
  import dm_env
  import numpy
  import reverb
  from rlds import rlds_types
  import tensorflow
  import tree
label_desc: Use image node_id 3 for calling the Actor obj's underlying member method code with example usage: obj.observe_first(timestep) without return types