如何使用gym 库中的仿真环境设计规则，设计了一个长 300m，宽 3.5 m 的单向双车道，其中包含5辆车，每辆车为一个智能体，每个智能体的状态空间为车辆的位置和速度，动作空间为车辆的加速度，奖励函数为R，终止条件为目标换道车辆到达换道终点，帮我设计满足上述要求的策略为LSTM的A3C算法代码

以下是使用gym库中的仿真环境设计规则，设计一个长300m，宽3.5m的单向双车道，每辆车为一个智能体，每个智能体的状态空间为车辆的位置和速度，动作空间为车辆的加速度，奖励函数为R，终止条件为目标换道车辆到达换道终点，并且使用LSTM的A3C算法的代码：

import gym
from gym import spaces
import numpy as np

class DoubleLaneEnv(gym.Env):
    """
    A double lane environment with 5 vehicles.
    """
    def __init__(self):
        self.length = 300  # length of the road
        self.width = 3.5  # width of the road
        self.num_agents = 5  # number of vehicles
        self.observation_space = spaces.Box(low=0, high=self.length, shape=(2*self.num_agents,))
        self.action_space = spaces.Box(low=-10, high=10, shape=(self.num_agents,))
        self.goal = self.length  # goal position
        self.reward_range = (-np.inf, np.inf)
        self.reset()

    def reset(self):
        self.agents = []
        for i in range(self.num_agents):
            agent_pos = np.random.uniform(low=0, high=self.length)
            agent_vel = np.random.uniform(low=0, high=30)
            self.agents.append({'pos': agent_pos, 'vel': agent_vel})
        self.current_agent = 0
        self.obs = np.array([agent['pos'] for agent in self.agents] + [agent['vel'] for agent in self.agents])
        self.done = False
        self.reward = 0
        return self.obs

    def step(self, action):
        if self.done:
            return self.obs, self.reward, self.done, {}

        agent = self.agents[self.current_agent]
        agent_vel = agent['vel']
        agent_pos = agent['pos'] + agent_vel + action

        # check if the agent has reached the goal
        if agent_pos >= self.goal:
            self.done = True
            self.reward = 1.0
            return self.obs, self.reward, self.done, {}

        # check for collisions
        for other_agent in self.agents:
            if other_agent['pos'] == agent_pos and other_agent['vel'] == agent_vel:
                self.done = True
                self.reward = -1.0
                return self.obs, self.reward, self.done, {}

        # update the position and velocity of the agent
        agent['pos'] = agent_pos
        agent['vel'] = agent_vel

        # update the observation
        self.obs = np.array([agent['pos'] for agent in self.agents] + [agent['vel'] for agent in self.agents])

        # calculate the reward
        self.reward = 0
        if agent_pos >= self.goal:
            self.reward = 1.0
        elif agent_pos >= self.width:
            self.reward = 0.1
        else:
            self.reward = -0.1

        # move to the next agent
        self.current_agent = (self.current_agent + 1) % self.num_agents

        return self.obs, self.reward, self.done, {}

class LSTM_A3C:
    def __init__(self, env, n_steps=5, n_hidden=32, lr=0.0001, gamma=0.99):
        self.env = env
        self.obs_shape = env.observation_space.shape
        self.action_shape = env.action_space.shape
        self.n_hidden = n_hidden
        self.lr = lr
        self.gamma = gamma
        self.n_steps = n_steps
        self.actor = self.build_network()
        self.critic = self.build_network()
        self.optimizer = tf.optimizers.Adam(lr)
        self.states = []
        self.actions = []
        self.rewards = []
        self.values = []
        self.episode_reward = 0

    def build_network(self):
        model = tf.keras.models.Sequential()
        model.add(tf.keras.layers.LSTM(self.n_hidden))
        model.add(tf.keras.layers.Dense(self.action_shape[0], activation='softmax'))
        return model

    def act(self, state):
        state = state.reshape(1, -1)
        probabilities = self.actor.predict(state)[0]
        action = np.random.choice(range(self.action_shape[0]), p=probabilities)
        return action, probabilities

    def remember(self, state, action, reward, value):
        self.states.append(state)
        self.actions.append(action)
        self.rewards.append(reward)
        self.values.append(value)

    def learn(self):
        # calculate discounted rewards
        discounted_rewards = np.zeros_like(self.rewards)
        running_reward = 0
        for t in reversed(range(len(self.rewards))):
            running_reward = running_reward * self.gamma + self.rewards[t]
            discounted_rewards[t] = running_reward

        # convert to tensors
        states = np.array(self.states)
        actions = np.array(self.actions)
        discounted_rewards = np.array(discounted_rewards)
        values = np.array(self.values)

        # calculate advantages
        advantages = discounted_rewards - values

        # calculate actor and critic losses
        with tf.GradientTape() as tape:
            logits = self.actor(states)
            action_masks = tf.one_hot(actions, self.action_shape[0])
            log_probs = tf.reduce_sum(action_masks * tf.math.log(logits), axis=1)
            actor_loss = -tf.reduce_mean(log_probs * advantages)

            value_preds = self.critic(states)
            critic_loss = tf.reduce_mean(tf.math.square(discounted_rewards - value_preds))

            total_loss = actor_loss + critic_loss

        # calculate gradients and update weights
        gradients = tape.gradient(total_loss, self.actor.trainable_variables + self.critic.trainable_variables)
        self.optimizer.apply_gradients(zip(gradients, self.actor.trainable_variables + self.critic.trainable_variables))

        # reset memory
        self.states = []
        self.actions = []
        self.rewards = []
        self.values = []

    def train(self, n_episodes=1000):
        for episode in range(n_episodes):
            state = self.env.reset()
            for t in range(self.n_steps):
                action, probs = self.act(state)
                next_state, reward, done, _ = self.env.step(action)
                value = self.critic.predict(state.reshape(1, -1))[0]
                self.remember(state, action, reward, value)
                self.episode_reward += reward
                state = next_state
                if done or t == self.n_steps-1:
                    self.learn()
                    break
            print('Episode: {}, Reward: {:.2f}'.format(episode+1, self.episode_reward))
            self.episode_reward = 0

    def test(self, n_episodes=10):
        for episode in range(n_episodes):
            state = self.env.reset()
            done = False
            while not done:
                action, probs = self.act(state)
                next_state, reward, done, _ = self.env.step(action)
                state = next_state
                self.episode_reward += reward
            print('Episode: {}, Reward: {:.2f}'.format(episode+1, self.episode_reward))
            self.episode_reward = 0

这个代码中，我们首先定义了一个名为 `DoubleLaneEnv` 的类，该类继承了 `gym.Env` 类，并定义了仿真环境的状态空间、动作空间和奖励函数等。然后，我们定义了一个名为 `LSTM_A3C` 的类，该类实现了LSTM的A3C算法，并使用 `DoubleLaneEnv` 类创建了一个仿真环境。最后，我们在 `train()` 和 `test()` 方法中训练和测试模型。