def format_amount_and_units(self, amount_sat, *, timestamp: int = None) -> str:
        """Returns string with both bitcoin and fiat amounts, in desired units.
        E.g. 500_000 -> '0.005 BTC (191.42 EUR)'
        """
        text = self.config.format_amount_and_units(amount_sat)
        fiat = self.fx.format_amount_and_units(amount_sat, timestamp=timestamp) if self.fx else None
        if text and fiat:
            text += f' ({fiat})'
        return text
Returns string with both bitcoin and fiat amounts, in desired units.
        E.g. 500_000 -> '0.005 BTC (191.42 EUR)'
        
electrum/gui/qt/main_window.py