<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def get_open_orders(self, asset=None):
 """Retrieve all of the current open orders. Parameters asset : Asset If passed and not None, return only the open orders for the given asset instead of all open orders. Returns ------- open_orders : dict[list[Order]] or list[Order] If no asset is passed this will return a dict mapping Assets to a list containing all the open orders for the asset. If an asset is passed then this will return a list of the open orders for this asset. """

        if asset is None:
            return {
                key: [order.to_api_obj() for order in orders]
                for key, orders in iteritems(self.blotter.open_orders)
                if orders
            }
        if asset in self.blotter.open_orders:
            orders = self.blotter.open_orders[asset]
            return [order.to_api_obj() for order in orders]
        return []