class_docstr: Adder wrapper substituting PWIL rewards.
code: def add_first(self, timestep: dm_env.TimeStep):
      self._rewarder.reset()
      self._latest_observation = timestep.observation
      self._adder.add_first(timestep)
  
file_path: acme/acme/agents/jax/pwil/adder.py
imports: from acme import adders
  from acme import types
  from acme.agents.jax.pwil import rewarder
  import dm_env
label_desc: Use image node_id 2 for calling the PWILAdder obj's underlying member method code with example usage: obj.add_first(timestep) without return types