new_contents: from abc import ABCMeta
  from collections import UserList
  
  
  class TooManyOrders(ValueError):
      pass
  
  
  class OrderList(UserList, metaclass=ABCMeta):
      """An abstract order list"""
  
  
  class DefaultOrderList(OrderList):
      """
      An OrderList with max size three, like in the original game.
      Supports all Python list operations.
      """
  
      max_orders = 3  # type: int
  
      def __init__(self, orders=None):
          # This method is called every time an inherited list operation is run.
          # See the comment below https://docs.python.org/3/library/collections.html#collections.UserList.
          super().__init__()
          if orders is not None and len(orders) > self.max_orders:
              raise TooManyOrders("Bots can have at most {} orders; tried to have {}".format(self.max_orders, len(list)))
  
subject: Add helper classes