old_contents: class Trade(object):
      BUY = 0
      SELL = 1
      def __init__(self, trade_id, trade_type, base_currency, counter_currency,
          time, order_id, amount, price, fee=None):
          self.trade_id = trade_id
          self.trade_type = trade_type
          self.base_currency = base_currency
          self.counter_currency = counter_currency
          self.time = time
          self.order_id = order_id
          self.amount = amount
          self.price = price
          self.fee = fee
  
new_contents: class Trade(object):
      BUY = 0
      SELL = 1
      def __init__(self, trade_id, trade_type, base_currency, counter_currency,
          time, order_id, amount, price, fee=None):
          self.trade_id = trade_id
          self.trade_type = trade_type
          self.base_currency = base_currency
          self.counter_currency = counter_currency
          self.time = time
          self.order_id = order_id
          self.amount = amount
          self.price = price
          self.fee = fee
  
      def __str__(self):
          if self.trade_type == 0:
              ts = 'Buy'
          else:
              ts ='Sell'
          return '<%s of %.8f %s>' % (ts, self.amount, self.base_currency)
  
subject: add string representation