old_contents: # coding: utf-8
  
  import numpy as np
  import torch
  from torch import nn
  from torch import optim
  from torch import cuda
  from torch.autograd import Variable
  
  from .core import Agent
  from .replay_buffer import ReplayBuffer
  
  
  # TODO
  class PPOAgent(Agent):
      def __init__(self):
          pass
  
      def act(self, observation, reward, done):
          pass
  
      def save(self):
          pass
  
      def load(self):
          pass
  
new_contents: # coding: utf-8
  
  import numpy as np
  import torch
  from torch import nn
  from torch import optim
  from torch import cuda
  from torch.autograd import Variable
  
  from .core import Agent
  from .replay_buffer import ReplayBuffer
  
  
  # TODO
  class PPOAgent(Agent):
      def __init__(self):
          raise NotImplementedError
  
      def act(self, observation, reward, done):
          raise NotImplementedError
  
      def save(self):
          raise NotImplementedError
  
      def load(self):
          raise NotImplementedError
  
subject: Update ppo.py