code: def forward(self, obs, action):
      q = F.relu(self.l1(obs))
      q = F.relu(self.l2(paddle.concat([q, action], 1)))
      return self.l3(q)
  
file_path: PARL/examples/tutorials/parl2_dygraph/lesson5/homework/ddpg_quadrotor/quadrotor_model.py
imports: import parl
  import paddle
  import paddle.nn
  import paddle.nn.functional
label_desc: Use image node_id 2 for calling the Critic obj's underlying member method code with example usage: obj.forward(obs, action) and returns: self