private async Task GoToSellOfferVM()
        {
            if (_sellOfferVM == null)
            {
                _sellOfferVM = new SellOfferViewModel(Filter, _authenticationVM.User.User, _authenticationVM.User);
            }
            await _sellOfferVM.Load();

            DisplayedView = _sellOfferVM;
        }
        private void Logout()
        {
            _productVM         = null;
            _buyOfferVM        = null;
            _sellOfferVM       = null;
            _buyTransactionVM  = null;
            _sellTransactionVM = null;

            _authenticationVM.User.Password = null;
            IsUserAuthenticated             = false;
            DisplayedView = _authenticationVM;
        }