title: How to represent nested array with typescript
body: <p>Say I have an array of strings like:</p>
  <pre class="lang-js prettyprint-override"><code>const a = ['foo', ['aa'], [['zzz',['bar']]]];
      
  export const acceptsArray = (v: Array&lt;any&gt;) : string =&gt; {
     returns flattenDeep(v).join(' ');
  };
  </code></pre>
  <p>besides using <code>Array&lt;any&gt;</code> how can I represent a nested array of strings?</p>