Ibyuma bitagira umuyongani ibyuma bidafite inguni.Ahanini ikoreshwa mugusukura hejuru, gusiga irangi no kumanura ibyuma bidafite fer hamwe nibicuruzwa bitagira umwanda, bikora uburinganire bwubuso bumwe, kubwibyo bikwiriye cyane cyane kubanza kwitegura mbere yo gutwikira.