Appium code generates “SyntaxError: await is only valid in async function”

I have been following the Appium tutorial on the official website. After following the steps and adapting their code template to the resource names/paths on my machine, I ran the test.js file using node.js and got the following error:

const elementId = await client.findElement("accessibility id","TextField1");    client.elementSendKeys(elementId.ELEMENT, "Hello World!");
                  ^^^^^

SyntaxError: await is only valid in async function
    at new Script (vm.js:84:7)
    at createScript (vm.js:264:10)
    at Object.runInThisContext (vm.js:312:10)
    at Module._compile (internal/modules/cjs/loader.js:684:28)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:732:10)
    at Module.load (internal/modules/cjs/loader.js:620:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:560:12)
    at Function.Module._load (internal/modules/cjs/loader.js:552:3)
    at Function.Module.runMain (internal/modules/cjs/loader.js:774:12)
    at executeUserCode (internal/bootstrap/node.js:342:17)

This is the content of the source file:

const wdio = require("webdriverio");
const opts = {
  port: 4723,
  capabilities: {
    platformName: "Android",
    platformVersion: "8.1.0",
    deviceName: "Android Emulator",
    app: "/Users/guest/Downloads/ApiDemos-debug.apk",
    automationName: "UiAutomator2"
  }
};

const client = wdio.remote(opts);

const elementId = await client.findElement("accessibility id","TextField1");    
client.elementSendKeys(elementId.ELEMENT, "Hello World!");
const elementValue = await client.findElement("accessibility id","TextField1");
await client.getElementAttribute(elementValue.ELEMENT,"value").then((attr) => {
	assert.equal(attr,"Hello World!");
});