code: def learn(self, obs, action, reward, next_obs, terminal):
      actor_cost = self.actor_learn(obs)
      critic_cost = self.critic_learn(
          obs, action, reward, next_obs, terminal
      )
      return critic_cost, actor_cost
  
file_path: PARL/parl/algorithms/fluid/sac.py
imports: from parl.core.fluid import layers
  from copy import deepcopy
  import numpy
  from paddle import fluid
  from paddle.fluid.layers import Normal
  from parl.core.fluid.algorithm import Algorithm
label_desc: Use image node_id 4 for calling the SAC obj's underlying member method code with example usage: obj.learn(obs, action, reward, next_obs, terminal) and returns: critic_cost,  actor_cost