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))