bool UserIdInGroup(string userId, string groupName);
bool UserInGroup(int userId, string groupName);
bool UserInGroup(string userName, string groupName);
bool AddUserIdToGroup(string userId, string groupName);
bool AddUserToGroup(int userId, string groupName);
bool AddUserToGroup(string userName, string groupName);
bool RemoveUserIdFromGroup(string userId, string groupName);
bool RemoveUserFromGroup(int userId, string groupName);
bool RemoveUserFromGroup(string userName, string groupName);