title: Recursive get ID
body: <p>haloa!</p>
  
  <p>i have a <code>List&lt;Channel&gt;</code> where <code>Channel</code> is a custom class offcourse:</p>
  
  <pre><code>public class Channel 
  {
      public long ID { get; set; }
      public long parentID { get; set; }
  }
  </code></pre>
  
  <p>strcuture can be something like:</p>
  
  <pre><code>ID = 1, parentID = 0
      ID = 64, parentID = 1
          ID = 28, parentID = 64
          ID = 36, parentID = 64
  ID = 5, parentID = 0
  </code></pre>
  
  <p>and so on.</p>
  
  <p>what i would like to do is get all children ID's of a specific channel:</p>
  
  <pre><code>function List&lt;long&gt; getChildrenIDS (long ID)
  {
      // WHAT GOES HERE?
  }
  </code></pre>