yield format_one_rate(rate, 1, to_curr, from_curr)

def run(config, stdout, stderr):

    loaders = config.get_loaders()

    with loaders.historical(config.args.date, config.args.base) as rate_json:

        rate = oxrrate.Rate.from_json_file(rate_json)

    if not config.args.from_currency:

        for from_curr in sorted(rate.rates):

            print(*format_rate_pair(rate, from_curr, config.args.to_currency),

                  sep='\n', file=stdout)

    elif config.args.amount is None:

        print(*format_rate_pair(rate, config.args.from_currency, config.args.to_currency),

    def _respond(self, *args, **kwargs):

        return open(self.response_path)

    def __getattr__(self, name):

        return self._respond

class FakeConfig:

    def __init__(self, responder, argvars=None):

        self.responder = responder

        self.args = argparse.Namespace()

        if argvars is not None: