我正在嘗試使用slack web api向用戶發送直接消息，但我認為獲取所有可用用戶的getSlackUser 方法在我調用 slackId 時沒有及時完成；console.log(slackId) 給出了未定義的意思，它沒有用bolt完成我的 api 調用如何確保 getSlackUser 方法在繼續執行其他方法之前完成（使其阻塞）？const { WebClient } = require('@slack/web-api');const { App } = require('@slack/bolt')const rtm = new RTMClient(process.env.SLACK_OAUTH_TOKEN);const web = new WebClient(process.env.SLACK_OAUTH_TOKEN);const app = new App({  token: process.env.SLACK_OAUTH_TOKEN,  signingSecret: process.env.SLACK_SIGNING_SECRET});exports.handler = async (event) => {  const slackId = await getSlackUser('example_real_name').id;  console.log(slackId);  await sendSlackMessage(slackId, 'Bot message');}sendSlackMessage = async (channel, message) => {  await web.chat.postMessage({    channel: channel,    text: message,    as_user: true  });}getSlackUser = async(real_name) => {  const result = await app.client.users.list({    token: process.env.SLACK_OAUTH_TOKEN  });  console.log(result);  return result.members.find((user) => user.real_name == real_name);}