/// <summary>
 /// search users
 /// http://developer.github.com/v3/search/#search-users
 /// </summary>
 /// <param name="request"></param>
 /// <returns>List of users</returns>
 public IObservable<User> SearchUsers(SearchUsersRequest request)
 {
     Ensure.ArgumentNotNull(request, "request");
     return _connection.GetAndFlattenAllPages<User>(ApiUrls.SearchUsers(), request.ToParametersDictionary());
 }