private async Task GoToBuyOfferVM()
        {
            if (_buyOfferVM == null)
            {
                _buyOfferVM = new BuyOfferViewModel(Filter, _authenticationVM.User.User, _authenticationVM.User);
            }
            await _buyOfferVM.Load();

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

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