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