题解 | #禁止重复注册#

import sys
current_users = ['Niuniu','Niumei','GURR','LOLO']
current_users_L=list((i.lower() for i in current_users))
new_users=['GurR','Niu Ke Le','LoLo','Tuo Rui Chi']

for s in new_users:
    if s.lower() in  current_users_L:
        print('The user name {} has already been registered! Please change it and try again!'.format(s))
    else:
        print('Congratulations, the user name {} is available!'.format(s))