We have seen how to implement queues using arrays, linked lists, and deques. You can also implement a queue with two stacks. The following methods implement a queue's enqueue and dequeue operations, but the interactions (method invocations) with the two stack objects have been removed. Fill in the missing portions. Use the minimum spacing possible. Assume that the stack objects are attributes of the queue class called self.__arrival_stack and self.__departure_stack and have the following methods:

push(item) pop() __len__()

def enqueue(self, value): self.__arrival_stack. ______ def dequeue(self): if len( ________)==0: while len(________)>0: __________ return ________