class_docstr: A recurrent actor.
class_docstr_tok: ["A","recurrent","actor","."]
code: def observe_first(self, timestep: dm_env.TimeStep):
      if self._adder:
          self._adder.add_first(timestep)
  
      # Set the state to None so that we re-initialize at the next policy call.
      self._state = None
  
file_path: acme/acme/agents/tf/impala/acting.py
imports: from typing import Optional
  from acme import adders
  from acme import core
  from acme import types
  from acme.tf import utils
  from acme.tf import variable_utils
  import dm_env
  import sonnet
  import tensorflow
  import tensorflow_probability
label_desc: Use image node_id 3 for calling the IMPALAActor obj's underlying member method code with example usage: obj.observe_first(timestep) without return types