创建的列表
sandwich_orders
，并确保
'pastrami'
在其中至少出现了三次。在程序开头附近添加
这样的代码：打印一条消息，指出熟食店的五香烟熏牛肉卖完了；再使用一个
while
循环将列表
sandwich_orders
中的
'pastrami'
都删除。确认最终的列
表
finished_sandwiches
中不包含
'pastrami'
——————————————————————————————————————代码如下：
sandwich_orders = ['bacon_egg_sandwich', 'ham_egg_sandwich', 'lettuce_ham_egg_sandwich']
# count = len(sandwich_orders)
# finished_sandwich = []
# while count > 0:
# finish_sandwich = sandwich_orders.pop()
# finished_sandwich.append(finish_sandwich)
# print('I made your %s sandwich!' %(finish_sandwich))
# count -= 1
# print(finished_sandwich)
# print(sandwich_orders)
count = 0
finished_sandwich = []
active = True
while active:if count < 3:sandwich_orders.append('pastrami')count += 1if 'pastrami' in sandwich_orders:sandwich_orders.remove('pastrami')finished_sandwich.append(sandwich_orders.pop())if len(sandwich_orders) == 0:break
print(finished_sandwich)