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