Put the various losses in the recorder and show a sample image.

def on_epoch_end(self, pbar, epoch, last_metrics, **kwargs):
        "Put the various losses in the recorder and show a sample image."
        if not hasattr(self, 'last_gen') or not self.show_img: return
        data = self.learn.data
        img = self.last_gen[0]
        norm = getattr(data,'norm',False)
        if norm and norm.keywords.get('do_y',False): img = data.denorm(img)
        img = data.train_ds.y.reconstruct(img)
        self.imgs.append(img)
        self.titles.append(f'Epoch {epoch}')
        pbar.show_imgs(self.imgs, self.titles)
        return add_metrics(last_metrics, [getattr(self.smoothenerG,'smooth',None),getattr(self.smoothenerC,'smooth',None)])