class RingMessageManager extends AbstractMessageManager {

  /**
   * Constructor of RingMessageManager.
   */
  public RingMessageManager(Map<Integer, Instance> instanceMap) {
    super(instanceMap);
  }

  /**
   * Send heartbeat message to current leader instance to check the health.
   *
   * @param leaderId leaderID
   * @return {@code true} if the leader is alive.
   */
  @Override
  public boolean sendHeartbeatMessage(int leaderId) {
    var leaderInstance = instanceMap.get(leaderId);
    var alive = leaderInstance.isAlive();
    return alive;
  }

  /**
   * Send election message to the next instance.
   *
   * @param currentId currentID
   * @param content   list contains all the IDs of instances which have received this election
   *                  message.
   * @return {@code true} if the election message is accepted by the target instance.
   */
  @Override
  public boolean sendElectionMessage(int currentId, String content) {
    var nextInstance = this.findNextInstance(currentId);
    var electionMessage = new Message(MessageType.ELECTION, content);
    nextInstance.onMessage(electionMessage);
    return true;
  }

  /**
   * Send leader message to the next instance.
   *
   * @param currentId Instance ID of which sends this message.
   * @param leaderId  Leader message content.
   * @return {@code true} if the leader message is accepted by the target instance.
   */
  @Override
  public boolean sendLeaderMessage(int currentId, int leaderId) {<FILL_FUNCTION_BODY>}

  /**
   * Send heartbeat invoke message to the next instance.
   *
   * @param currentId Instance ID of which sends this message.
   */
  @Override
  public void sendHeartbeatInvokeMessage(int currentId) {
    var nextInstance = this.findNextInstance(currentId);
    var heartbeatInvokeMessage = new Message(MessageType.HEARTBEAT_INVOKE, "");
    nextInstance.onMessage(heartbeatInvokeMessage);
  }

}

    var nextInstance = this.findNextInstance(currentId);
    var leaderMessage = new Message(MessageType.LEADER, String.valueOf(leaderId));
    nextInstance.onMessage(leaderMessage);
    return true;
  
<methods>public void <init>(Map<java.lang.Integer,com.iluwatar.leaderelection.Instance>) <variables>protected Map<java.lang.Integer,com.iluwatar.leaderelection.Instance> instanceMap