private void welcomeNewUser(User newUser)
        {
            TextMessage welcomeMessage = new TextMessage($"Welcome, {newUser.Name}", ServerDTO.AdminData, (UserData)newUser.Data);

            ServerDTO.Serializer.Serialize(newUser.nwStream, welcomeMessage);
            ContactsMessage newContactsDBMessage = new ContactsMessage(ServerDTO.ContactsDB, ServerDTO.AdminData, ServerDTO.AdminData);

            _messageSender.SendToAllClients(newContactsDBMessage);
            TextMessage userJoinedChatMessage = new TextMessage($"{newUser.Name} joined the chat!", ServerDTO.AdminData, ServerDTO.AdminData);

            _messageSender.SendToAllClients(userJoinedChatMessage);
        }
        private void removeUserFromMembersDB(TcpClient client)
        {
            User     removedUser     = _serverDTO.MembersDB.RemoveUser(client);
            UserData removedUserData = (UserData)removedUser.Data;

            removeUserFromContactsDB(removedUserData);
            if (removedUser != null)
            {
                TextMessage userLeftChatMessage = new TextMessage($"{removedUser.Name} has left the chat!", _serverDTO.AdminData, _serverDTO.AdminData);
                _messageSender.SendToAllClients(userLeftChatMessage);
                ContactsMessage contactsUpdateMessage = new ContactsMessage(_serverDTO.ContactsDB, _serverDTO.AdminData, _serverDTO.AdminData);
                _messageSender.SendToAllClients(contactsUpdateMessage); // ToDo: move to a function with indicative name
            }
        }