import sys current_users = ['Niuniu','Niumei','GURR','LOLO'] new_users = ['GurR','Niu Ke Le','LoLo','Tuo Rui Chi'] current_users1 = [i.lower() for i in current_users] for j in new_users: a = j.lower() in current_users1 if a: print('The user name %s has already been re...