How to use the viber-bot.Events.MESSAGE_RECEIVED function in viber-bot

function ViberEnabledConnector(opts) {
        var self = this;
        this.options = opts || {};
        this.viberBot = new ViberBot({
            authToken: this.options.Token,
            name: this.options.Name,
            // It is recommended to be 720x720, and no more than 100kb.
            avatar: this.options.AvatarUrl,
            logger: logger
        });

        this.viberBot.on(BotEvents.MESSAGE_RECEIVED, (message, response) => {
            self.processMessage(message, response);
        });

        this.viberBot.on(BotEvents.CONVERSATION_STARTED, (response, onFinish) => {
            // onFinish(new TextMessage(`Hi, ${userProfile.name}! Nice to meet you.`))
            var self = this;
            var userProfile = response.userProfile;
            var addr = {
                channelId: ViberChannelId,
                user: { id: encodeURIComponent(userProfile.id), name: userProfile.name },
                bot: { id: 'viberbot', name: self.options.Name },
                conversation: { id: 'ViberConversationId' }
            };

            var msg = new builder.Message()
                .address(addr)

mbfBot.on(MbfEvents.MBF_MESSAGE_RECEIVED, function(recipient, message) {
    // send a MBF bot message back to Viber
    bot.sendMessage(recipient, message);
});

bot.onSubscribe(response => {
    // create a connection to the MBF bot
    mbfBot.createNewConversation(response.userProfile);
});

bot.onUnsubscribe(response => {
    mbfBot.closeConversation(response);
})

bot.on(BotEvents.MESSAGE_RECEIVED, (message, response) => {
    // send an user message to the MBF bot
    mbfBot.sendMessage(response.userProfile, message);
});

var webHookUrl = process.env.WEBSERVER_URL || WebServerUrl;
if (webHookUrl) {
    const http = require('http');
    const port = process.env.WEBSERVER_PORT || WebServerPort;

    http.createServer(bot.middleware()).listen(port, () => bot.setWebhook(webHookUrl));
} else {
    logger.debug('Could not find the now.sh/Heroku environment variables. Please make sure you followed readme guide.');
}

public listen(): Observable {
    if (!this.session) {
      return Observable.throw(new Error('No session found.'));
    }

    return Observable.fromEvent(
      this.session,
      Events.MESSAGE_RECEIVED,
      (...args) => ({ message: args[0], user_profile: args[1].userProfile }))
      .mergeMap((event: any) => this.parser.normalize(event))
      .mergeMap((normalized: any) => {
        if (!normalized) { return Promise.resolve(null); }

        const id: any = R.path(['author', 'id'], normalized);
        if (id) {
          this.storeUsers.set(id as string, normalized.author);
        }
        if (this.me) {
          normalized.target = this.me;
          return Promise.resolve(normalized);
        }

        return this.session.getBotProfile()
          .then((profile: any) => {

public listen(): Observable {
    if (!this.session) {
      return Observable.throw(new Error("No session found."));
    }

    return Observable.fromEvent(this.session, Events.MESSAGE_RECEIVED,
      (...args) => ({ message: args[0], user_profile: args[1].userProfile }))
      .mergeMap((event: any) => this.parser.normalize(event))
      .mergeMap((normalized: any) => {
        if (!normalized) { return Promise.resolve(null); }

        const id: any = R.path(["author", "id"], normalized);
        if (id) {
          this.storeUsers.set(id as string, normalized.author);
        }
        if (this.me) {
          normalized.target = this.me;
          return Promise.resolve(normalized);
        }

        return this.session.getBotProfile()
          .then((profile: any) => {

public listen(): Observable {
    if (!this.session) {
      return Observable.throw(new Error("No session found."));
    }

    return Observable.fromEvent(this.session, Events.MESSAGE_RECEIVED,
      (...args) => ({ message: args[0], user_profile: args[1].userProfile }))
      .mergeMap((event: any) => this.parser.normalize(event))
      .mergeMap((normalized: any) => {
        if (!normalized) { return Promise.resolve(null); }

        const id: any = R.path(["author", "id"], normalized);
        if (id) {
          this.storeUsers.set(id as string, normalized.author);
        }
        if (this.me) {
          normalized.target = this.me;
          return Promise.resolve(normalized);
        }

        return this.session.getBotProfile()
          .then((profile: any) => {