code: def observe(self, obs):
      self.retriever.observe(obs)
      self.observation = obs
  
file_path: ParlAI/parlai/agents/retriever_reader/retriever_reader.py
imports: from typing import Optional
  from parlai.core.params import ParlaiParser
  from parlai.core.opt import Opt
  from parlai.core.agents import Agent
  from parlai.core.agents import create_agent
  import regex
label_desc: Use image node_id 3 for calling the RetrieverReaderAgent obj's underlying member method code with example usage: obj.observe(obs) without return types