code: def recalculate_stock_values_into_base(self):
          
          from .currency import CurrencyConverter
  
          conv = CurrencyConverter()
          cash = self.model.get_cash_asset_class()
  
          for stock in self.model.stocks:
              if stock.currency != self.base_currency:
                  # Recalculate into base currency
                  conv.load_currency(stock.currency)
                  assert isinstance(stock.value, Decimal)
                  val_base = stock.value * conv.rate.value
              else:
                  # Already in base currency.
                  val_base = stock.value
  
              stock.value_in_base_currency = val_base
docs: Loads the exchange rates and recalculates stock holding values into 
          base currency