title: Custom Collection Implementing IEnumerable
body: <p>I know that technically, an Interface is used for reading and not writting or editing however, I want to add an add and addrange function to the following class, here is what I currently have which is not working</p>
  
  <pre><code>public class HrefCollection : IEnumerable&lt;Href&gt; 
  {
      private IEnumerable&lt;Href&gt; hrefs;
  
      public IEnumerable&lt;Href&gt; Add( Href href )
      {
          yield return href;
      }
  
      public IEnumerable&lt;Href&gt; AddRange( List&lt;Href&gt; hrefs )
      {
          foreach( Href href in hrefs )
          {
              yield return href;
          }
      }
  
      public IEnumerator&lt;Href&gt; GetEnumerator()
      {
          return hrefs.GetEnumerator();
      }
  
      System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()
      {
          return hrefs.GetEnumerator();
      }
  }
  </code></pre>
  
  <p>I'm not quite sure how to associate the yield return with the private list.</p>
  
  <p>Thanks for your help!</p>