code: def create_agent(self, env):
      model = create_state_q_function_for_env(env)
      rbuf = replay_buffer.ReplayBuffer(10**5)
      opt = optimizers.Adam()
      opt.setup(model)
      explorer = explorers.ConstantEpsilonGreedy(
          0.2, random_action_func=lambda: env.action_space.sample()
      )
      return agents.DQN(model, opt, rbuf, gamma=0.99, explorer=explorer)
  
imports: from chainer import optimizers
  from chainer import testing
  import gym
  import gym.spaces
  import basetest_agents
  from chainerrl import agents
  from chainerrl import explorers
  from chainerrl import policies
  from chainerrl import q_functions
  from chainerrl import replay_buffer
  from chainerrl import v_function
label_desc: Use image node_id 1 for calling the TestDQN obj's underlying member method code with example usage: obj.create_agent(env) and returns: agents