code: def sample(self, obs):
      means, logvars = self.policy(obs)
      sampled_act = means + (
          layers.exp(logvars / 2.0)
          * layers.gaussian_random(  # stddev
              shape=(self.act_dim,), dtype="float32"
          )
      )
      return sampled_act
  
file_path: PARL/benchmark/fluid/PPO/mujoco_model.py
imports: import numpy
  import parl
  from parl import layers
  from paddle import fluid
  from paddle.fluid.param_attr import ParamAttr
label_desc: Use image node_id 3 for calling the PolicyModel obj's underlying member method code with example usage: obj.sample(obs) and returns: sampled_act