title: access my component's child, rebuild it and put it back
body: <p>For any <code>div</code> or <code>h1</code> or whatever within my own component like the following:</p>
  
  <pre><code>&lt;app-my-comp&gt;
      &lt;div&gt;original div&lt;/div&gt;
  &lt;/app-my-comp&gt;
  </code></pre>
  
  <p>I would like to transform it to the following on rendering:</p>
  
  <pre><code>&lt;div class="..." someAttribute="someValue"&gt;
     &lt;div&gt;original div&lt;/div&gt;
     &lt;div&gt;a new div generated by my component&lt;/div&gt;
     &lt;div&gt;another new div generated by my component&lt;/div&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>How can I achieve this? I have absolutely no ideas at all so I don't even know how to google.</p>