<pre class="shiki github-dark shaku"><code>/** * @param {any[]} args * @returns {string} */function classNames(...args) { // your code here return args.map(item =&gt; { if (item &amp;&amp; typeof item === 'object') { return Array.isArray(item) ? classNames(...Array.prototype.flat.call(item, Infinity)) : classNames(...Object.keys(item).filter(key =&gt; item[key])); } return (typeof item === 'string' || typeof item === 'number') ? item : ''; }).filter(item =&gt; item).join(' ').trim();}</code></pre>