public ChatGroupList GetGroupByUserId(string id)
        {
            ChatGroupList chatGroupList = new ChatGroupList();

            foreach (var group in GroupList)
            {
                if (group.HasId(id))
                {
                    chatGroupList.AddNewGroup(group);
                }
            }
            return(chatGroupList);
        }
        public ChatGroupList GetGroupByCreatorId(string id)
        {
            ChatGroupList chatGroupList = new ChatGroupList();

            foreach (var group in GroupList)
            {
                if (group.CreatorId == id)
                {
                    chatGroupList.AddNewGroup(group);
                }
            }
            return(chatGroupList);
        }