How to add a new image in dataloaders ? not only x, y

fastai
1 
def get_dls(bs, size):
    dblock = DataBlock(
        blocks=(ImageBlock, ImageBlock),
        get_items=get_image_files,
        splitter=RandomSplitter(0.1),
        get_y=lambda x: path_anime/x.name,   
        item_tfms=Resize(size),
        batch_tfms = [*aug_transforms(),normalize11] 
    )
    dls = dblock.dataloaders(path_photo, bs=bs, num_workers=0)
    dls.c = 3
    return dls

when I train a model, I want input are x, y, x_mask, y_mask, use the pair mask to supervised learning. but I don’t know how to add , I only get x and y .