title: Augmenting an interface that lives in a declared namespace in TypeScript
body: <p>I want to augment the <code>IHttpPromise&lt;T&gt;</code> inside the declared angular namespace (from "@types/angular"). So that I'll be able to write <code>$http.then(...).myCustomMethod(...)</code>.</p>
  
  <p>I was able to augment interfaces in the global context easily by just writing:</p>
  
  <pre><code>interface JQuery {
      $custom: string;
  }
  </code></pre>
  
  <p>For interfaces inside namespaces, the same doesn't work obviously. Tried several things like declaring the <code>angular</code> namespace again and putting the augmented interface inside, but that and other numerous variations didn't work.</p>
  
  <p>Note that I'm not using (external) modules.</p>