typecast problem with List class
<p>What is the bug here?</p>

<pre><code>private void LoadUsers(List&lt;long&gt; uids, EventUser.EventUserStatus eventUserStatus, IList&lt;user&gt; chkfriends)
{
    foreach (var f in chkfriends) 
    {
      long l = f.uid; &lt;-- fails
       if (uids.Contains(l)) do it!
    }
</code></pre>

<p>Error   1   Cannot implicitly convert type 'long?' to 'long'. An explicit conversion exists (are you missing a cast?)</p>
