code: def learn(self):
      total_loss, pi_loss, vf_loss, entropy = self.learn_exe.run(
          fetch_list=self.learn_outputs
      )
      return total_loss, pi_loss, vf_loss, entropy
  
file_path: PARL/benchmark/fluid/GA3C/atari_agent.py
imports: import numpy
  import paddle.fluid
  import parl
  from parl import layers
  from parl.utils import machine_info
label_desc: Use image node_id 5 for calling the AtariAgent obj's underlying member method code with example usage: obj.learn() and returns: total_loss,  pi_loss,  vf_loss,  entropy