angular2 - How do 'imports' and 'exports' work in Angular2 modules? : <p>I am completely new to Angular2 and it has been very difficult to understand what is going on with the <code>@NgModule</code> <strong>imports and exports in Angular2.</strong></p>

<p>Take the following code for example-:</p>

<pre><code>@NgModule({
  imports: [
    RouterModule.forChild(heroesRoutes)
  ],
  exports: [
    RouterModule
  ]
})
</code></pre>

<p>In the imports section <strong>what am I importing ?</strong> <em>The router module , or the forChild() function, or the module returned by the function forChild() ?</em>
Which one is it ?</p>

<p>Also when I export the <code>RouterModule</code> again, the <a href="https://angular.io/docs/ts/latest/guide/router.html#!#routing-module" rel="noreferrer">documentation</a> says the following-:</p>

<blockquote>
  <p>Our last step is to re-export the RouterModule. By re-exporting the
  RouterModule, our feature module will be provided with the Router
  Directives when using our Routing Module.</p>
</blockquote>

<p><strong>So does that mean that whatever module imports the above NgModule, will have access to all the code in the RouterModule ?</strong> </p>

<p>Is it sort of like if I write a custom header file in C that includes math.h, if I now use that header file I no longer need to include math.h in my programme separately. <em>Is my analogy correct ?</em></p>

<p>Can someone explain the core concepts here, so that I don't get stumped every time I see new code.</p>
