#创建一个待验证的用户列表
#和一个用于存储已经验证的用户列表
unconfirmed_users = ["alice", "brian", "candace"]
confirmed_users = []

#验证每个用户,直到没有未验证的用户
while unconfirmed_users:
    current_user = unconfirmed_users.pop()

    print("Verifying user: " + current_user.title())
    confirmed_users.append(current_user)

print("\nThe following users have been confirmed:")
for confirmed_user in confirmed_users:
    print(confirmed_user.title())