class BeancountFormatter(LedgerFormatter):

    COST_FMT = '{{{}}}'

    def __init__(self, cost_rates, price_rates=None,

                 signed_currencies=(), base_fmt='###0.###',

                 rate_precision=5, denomination=None):

        super().__init__(

            cost_rates,

            price_rates,

            (),

            base_fmt.replace(',', ''),

            rate_precision,

            denomination,

        )

    def price_rate(self, from_amt, from_curr, to_curr):

        if self.price_rates is None:

            return None

        else:

            return self.price_rates.convert(from_amt, from_curr, to_curr)

    BEANCOUNT = BeancountFormatter