code: def test_ddpg_popart():
      """
      Test DDPG with pop-art normalization
      """
      n_actions = 1
      action_noise = NormalActionNoise(
          mean=np.zeros(n_actions), sigma=0.1 * np.ones(n_actions)
      )
      model = DDPG(
          "MlpPolicy",
          "Pendulum-v0",
          memory_limit=50000,
          normalize_observations=True,
          normalize_returns=True,
          nb_rollout_steps=128,
          nb_train_steps=1,
          batch_size=64,
          action_noise=action_noise,
          enable_popart=True,
      )
      model.learn(NUM_TIMESTEPS)
  
file_path: stable-baselines/tests/test_continuous.py
imports: import subprocess
  import os
  import gym
  import pytest
  import numpy
  from stable_baselines import A2C, ACKTR, SAC, DDPG, PPO1, PPO2, TRPO, TD3
  from stable_baselines.common.vec_env import DummyVecEnv
  from stable_baselines.common.identity_env import IdentityEnvBox
  from stable_baselines.ddpg import AdaptiveParamNoiseSpec, NormalActionNoise
  from stable_baselines.common.evaluation import evaluate_policy
  from tests.test_common import _assert_eq
label_desc: Use image node_id 5 for calling a global function with example usage: test_ddpg_popart() without return types