title: index signature and typed key in TS?
body: <p>The following code will always produce an error, but as a sketch, this is what I aim to represent:</p>
  <pre class="lang-js prettyprint-override"><code>interface A  {
      [ key : string ] : string, 
      &quot;anotherKey&quot; : MyInterface
  }
  </code></pre>
  <p>I've checked a few books, TS documentation, tested in <strong>ts-node</strong>, but I am not that well versed and need some help.</p>
  <p>How can I specify an object whose most keys are <code>&quot;key&quot;:&quot;value&quot;</code>  but some specific aren't?</p>