docstr: 根据观测值 obs 选择最优动作
          
code: def predict(self, obs):
      """根据观测值 obs 选择最优动作"""
      obs = paddle.to_tensor(obs.reshape(1, -1), dtype="float32")
      action = self.alg.predict(obs)
      action_numpy = action.cpu().numpy()[0]
      action_numpy = action_numpy.clip(-1, 1)
      return action_numpy
  
file_path: PARL/examples/tutorials/parl2_dygraph/lesson5/ddpg/agent.py
imports: import parl
  import paddle
  import numpy
label_desc: Use image node_id 3 for calling the Agent obj's underlying member method code with example usage: obj.predict(obs) and returns: action_numpy