> How does the person who wrote the code know what exact thing you don’t understand? The suggested alternative, "If this is an optimization, can you please add

> How does the person who wrote the code know what exact thing you don’t understand? The suggested alternative, "If this is an optimization, can you please add comments?", is a guess. Are we supposed to guess what uncommented code does, and put those guesses in the code review? That sounds even more unproductive than just saying "I don't understand".