trys pop(print("test failed" except runtimeerrorprint("test passed"exceptprint("test failed" trys top(print("test failed" except runtimeerrorprint("test passed"exceptprint("test failed" if __name__=="__main__"main(this codeif saved in file called stack py can be imported into other modules when this module is run by itselfthe test main function will execute when this module is imported into another programthe main function will not execute because the __name__ variable will not be equal to "__main__a queue is like stack in many ways except that instead of being lifo data structurequeues are fifo or first in/first out data structures the first item pushedis the first item popped when we are working with queue we talk of enqueueing an iteminstead of pushing it when removing an item from the queue we talk of dequeueing the item instead of popping it as we did from stack the table in fig provides details of the queue operations and their complexities implementing queue with the complexities given in this table is bit trickier than implementing the stack to implement queue with these complexities we need to be able to add to one end of sequence and remove from the other end of the sequence in ( time this suggests the use of linked list certainlya linked list would work to get the desired complexities howeverwe can still use list if we are willing to accept an amortized complexity of ( for the dequeue operation this queue class code implements queue with list and achieves an amortized complexity of ( for the dequeue operation operation queue creation dequeue enqueue front isempty complexity ( ( ( ( ( usage =queue( = dequeue( enqueue(aa= front( isempty(description calls the constructor returns the first item enqueued and removes it from enqueues the itemaon the queueq returns the front item without dequeueing the item returns true if has not enqueued items fig complexity of queue operations this copy belongs to 'acha