':param trader_id: The trader id who created the order
:param order_number: The number of the order created
:type trader_id: TraderId
:type order_number: OrderNumber'

def __init__(self, trader_id, order_number):

    super(OrderId, self).__init__()
    assert isinstance(trader_id, TraderId), type(trader_id)
    assert isinstance(order_number, OrderNumber), type(order_number)
    self._trader_id = trader_id
    self._order_number = order_number
