code: def _test_load_ddpg(self, gpu):
      obs_size = 11
      action_size = 3
      from pfrl.nn import ConcatObsAndAction
  
      q_func = nn.Sequential(
          ConcatObsAndAction(),
          nn.Linear(obs_size + action_size, 400),
          nn.ReLU(),
          nn.Linear(400, 300),
          nn.ReLU(),
          nn.Linear(300, 1),
      )
      from pfrl.nn import BoundByTanh
      from pfrl.policies import DeterministicHead
  
      policy = nn.Sequential(
          nn.Linear(obs_size, 400),
          nn.ReLU(),
          nn.Linear(400, 300),
          nn.ReLU(),
          nn.Linear(300, action_size),
          BoundByTanh(low=[-1.0, -1.0, -1.0], high=[1.0, 1.0, 1.0]),
          DeterministicHead(),
      )
  
      opt_a = torch.optim.Adam(policy.parameters())
      opt_c = torch.optim.Adam(q_func.parameters())
  
      explorer = explorers.AdditiveGaussian(
          scale=0.1, low=[-1.0, -1.0, -1.0], high=[1.0, 1.0, 1.0]
      )
  
      agent = agents.DDPG(
          policy,
          q_func,
          opt_a,
          opt_c,
          replay_buffers.ReplayBuffer(100),
          gamma=0.99,
          explorer=explorer,
          replay_start_size=1000,
          target_update_method="soft",
          target_update_interval=1,
          update_interval=1,
          soft_update_tau=5e-3,
          n_times_update=1,
          gpu=gpu,
          minibatch_size=100,
          burnin_action_func=None,
      )
  
      downloaded_model, exists = download_model(
          "DDPG", "Hopper-v2", model_type=self.pretrained_type
      )
      agent.load(downloaded_model)
      if os.environ.get("PFRL_ASSERT_DOWNLOADED_MODEL_IS_CACHED"):
          assert exists
  
imports: import os
  import numpy
  import pytest
  import torch
  from torch import nn
  import pfrl
  import pfrl.nn
  from pfrl import agents, explorers, replay_buffers
  from pfrl.initializers import init_chainer_default
  from pfrl.utils import download_model
label_desc: Use image node_id 2 for calling the TestLoadDDPG obj's underlying member method code with example usage: obj._test_load_ddpg(gpu) without return types