but not tell us the attention mask there and it will make the attention mask into the true Y so at the end we can compare what our model output the attention mask we output here without ever knowing that it should be a square and we have the true label which comes out of the generator that at the beginning decided that it should be a square and then the loss in the distance between those two that's our loss this is an in this is an enormous procedure to get a loss and most crucially you have to back propagate through optimization