code: def value(self, obs):
      hid1 = self.fc1(obs)
      hid2 = self.fc2(hid1)
      hid3 = self.fc3(hid2)
      V = self.fc4(hid3)
      V = layers.squeeze(V, axes=[])
      return V
  
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 2 for calling the ValueModel obj's underlying member method code with example usage: obj.value(obs) and returns: V