code: def test_single_dqn_input():
      model = Sequential()
      model.add(Flatten(input_shape=(2, 3)))
      model.add(Dense(2))
  
      memory = SequentialMemory(limit=10, window_length=2)
      for double_dqn in (True, False):
          agent = DQNAgent(
              model,
              memory=memory,
              nb_actions=2,
              nb_steps_warmup=5,
              batch_size=4,
              enable_double_dqn=double_dqn,
          )
          agent.compile("sgd")
          agent.fit(MultiInputTestEnv((3,)), nb_steps=10)
  
file_path: keras-rl/tests/rl/agents/test_dqn.py
imports: from __future__ import division
  from __future__ import absolute_import
  import pytest
  import numpy
  from numpy.testing import assert_allclose
  from keras.models import Sequential, Model
  from keras.layers import Input, Dense, Flatten, Concatenate
  from rl.agents.dqn import NAFLayer, DQNAgent, NAFAgent
  from rl.memory import SequentialMemory
  from rl.processors import MultiInputProcessor
  from ..util import MultiInputTestEnv
label_desc: Use image node_id 1 for calling a global function with example usage: test_single_dqn_input() without return types