How to use the @slack/rtm-api.RTMClient function in @slack/rtm-api

private createRtmClient(token: string, logLabel: string): RTMClient {
        const LOG_LEVELS = ["debug", "info", "warn", "error", "silent"];
        const connLog = Logging.get(`RTM-${logLabel.substr(0, LOG_TEAM_LEN)}`);
        const logLevel = LOG_LEVELS.indexOf(this.main.config.rtm!.log_level || "silent");
        const rtm = new RTMClient(token, {
            logLevel: LogLevel.DEBUG, // We will filter this ourselves.
            logger: {
                getLevel: () => LogLevel.DEBUG,
                setLevel: () => {},
                setName: () => {}, // We handle both of these ourselves.
                debug: logLevel <= 0 ? connLog.debug.bind(connLog) : () => {},
                warn: logLevel <= 1 ? connLog.warn.bind(connLog) : () => {},
                info: logLevel <= 2 ? connLog.info.bind(connLog) : () => {},
                error: logLevel <= 3 ? connLog.error.bind(connLog) : () => {},
            } as Logger,
        });

        rtm.on("error", (error) => {
            // We must handle this lest the process be killed.
            connLog.error("Encountered 'error' event:", error);
        });

const { RTMClient } = require('@slack/rtm-api');
const { WebClient, retryPolicies } = require('@slack/web-api');
const Queue = require('smart-request-balancer');
const memoize = require('memoizee');

const Logger = require('../includes/logger.js');
const DB = require('./db.js');
const { PRIVATE_TEST_CHANNELS } = require('../consts.js');

const { SLACK_BOT_TOKEN, SLACK_USER_TOKEN } = process.env;
const RTM = new RTMClient(SLACK_BOT_TOKEN);

const PR_REGEX = /github\.com\/([\w-.]*)?\/([\w-.]*?)\/pull\/(\d+)/i;
const PR_REGEX_GLOBAL = new RegExp(PR_REGEX.source, `${PR_REGEX.flags}g`);

const user_client = new WebClient(SLACK_USER_TOKEN, {
  retryConfig: retryPolicies.rapidRetryPolicy,
});
const bot_client = new WebClient(SLACK_BOT_TOKEN, {
  retryConfig: retryPolicies.rapidRetryPolicy,
});

exports.bot_client = bot_client;
exports.user_client = user_client;

const balancer = new Queue({
  rules: {

createRtmRuntime(): void {
    const rtm = new RTMClient(this._accessToken);
    const handler = this.createRequestHandler();

    rtm.on('message', handler);
    rtm.start();
  }
}