题解 | #禁止重复注册#

current_users = ['Niuniu','Niumei','GURR','LOLO']
new_users = ['GurR','Niu Ke Le','LoLo','Tuo Rui Chi']
current_users_L = [i.lower() for i in current_users]
for i in new_users:
    if i.lower() in current_users_L:
        print('The user name {} has already been registered! Please change it and try again!'.format(i))
    else:
        print('Congratulations, the user name {} is available!'.format(i))