title: Is there a Module Tree in Angular application?
body: <p>I know that there is an Injector Tree and a component tree in an Angular Application. But I have 3 questions:</p>
  <ol>
  <li><p>Is there a Module Tree in an Angular application?</p>
  </li>
  <li><p>How to get a Module instance if it exists?</p>
  </li>
  <li><p>When I import my Shared Module into multi Feature Modules, do I get multi Shared Module instance, or just a singleton Shared Module instance?</p>
  </li>
  </ol>