private void handleUserList(BroadcastChatClient client, string channel)
 {
     if (!server.Channels.ContainsKey(channel))
     {
         client.SendErrorNoChannel(channel);
     }
     else if (!client.Channels.ContainsKey(channel))
     {
         client.SendErrorNotInChannel(channel);
     }
     else
     {
         StringBuilder sb = new StringBuilder();
         foreach (string cl in server.Channels[channel].Clients.Keys)
         {
             sb.AppendFormat(server.Channels[channel].OperClients.ContainsKey(cl) ? "@{0} " : "{0} ", cl);
         }
         client.SendUserList(channel, sb.ToString());
     }
 }