public string Add(UserSession userSession, string username)
 {
     string resultString = "";
     if (!userSession.IsUserBlocked(username))
     {
         userSession.BlockUser(username);
         resultString = String.Format(Lang.Trans("{0} has been added to your blocked list"), username);
     }
     else
     {
         resultString = Lang.Trans("Already in blocked list!");
     }
     
     return resultString;
 }