题解 | #禁止重复注册#

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