code: def step(self, obs):
      actions = self.get_actions(
          obs["observation"], obs["achieved_goal"], obs["desired_goal"]
      )
      return actions, None, None, None
  
imports: from collections import OrderedDict
  import numpy
  import tensorflow
  from tensorflow.contrib.staging import StagingArea
  from baselines import logger
  from baselines.her.util import import_function, store_args, flatten_grads, transitions_in_episode_batch, convert_episode_to_batch_major
  from baselines.her.normalizer import Normalizer
  from baselines.her.replay_buffer import ReplayBuffer
  from baselines.common.mpi_adam import MpiAdam
  from baselines.common import tf_util
label_desc: Use image node_id 4 for calling the DDPG obj's underlying member method code with example usage: obj.step(obs) and returns: actions,  None,  None,  None