禁止重复注册

• 题目的关键在于将列表的单词全部转化为小写，再比较

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 %s has already been registered! Please change it and try again!' % i)
    else:
        print('Congratulations, the user name %s is available!' %i)