code: def observe(self, terminal, reward, index=0):
          
          fetches = self.episode_output
          feed_dict = self.get_feed_dict(terminal=terminal, reward=reward, index=index)
  
          episode = self.monitored_session.run(fetches=fetches, feed_dict=feed_dict)
  
          return episode
docs: Adds an observation (reward and is-terminal) to the model without updating its trainable variables.
  
          Args:
              terminal (List[bool]): List of is-terminal signals.
              reward (List[float]): List of reward signals.
              index: (int) parallel episode you want to observe
  
          Returns:
              The value of the model-internal episode counter.