old_contents: class Order(object):
      '''
      Basic order
      '''
      order_type = 0
      def __init__(self, order_id, base_currency, counter_currency,
                  datetime, amount, price):
          self.order_id = order_id
          self.order_type = order_type
          self.base_currency = base_currency
          self.counter_currency = counter_currency
          self.datetime = datetime
          self.amount = amount
          self.price = price
  
      def type(self):
          return self.__class__.__name__
  
      def __str__(self):
          return repr(self.__dict__)
  
  class BuyOrder(Order):
      order_type = 1
  class SellOrder(Order):
      order_type = 2
  
new_contents: class Order(object):
      '''
      Basic order
      '''
      order_type = 0
      def __init__(self, order_id, base_currency, counter_currency,
                  datetime, amount, price):
          self.order_id = order_id
          self.base_currency = base_currency
          self.counter_currency = counter_currency
          self.datetime = datetime
          self.amount = amount
          self.price = price
  
      def type(self):
          return self.__class__.__name__
  
      def __str__(self):
          return repr(self.__dict__)
  
  class BuyOrder(Order):
      order_type = 1
  
  class SellOrder(Order):
      order_type = 2
  
subject: Remove order_type set from Order constructor