def stats(self, symbol):
        """
        curl https://api.bitfinex.com/v1/stats/btcusd
        [
            {"period":1,"volume":"7410.27250155"},
            {"period":7,"volume":"52251.37118006"},
            {"period":30,"volume":"464505.07753251"}
        ]
        """
        data = self._get(self.url_for(PATH_STATS, (symbol)))

        for period in data:

            for key, value in period.items():
                if key == 'period':
                    new_value = int(value)
                elif key == 'volume':
                    new_value = float(value)

                period[key] = new_value

        return data
curl https://api.bitfinex.com/v1/stats/btcusd
        [
            {"period":1,"volume":"7410.27250155"},
            {"period":7,"volume":"52251.37118006"},
            {"period":30,"volume":"464505.07753251"}
        ]