__next__.py

    def __next__(self):
        if self.ilength <= 0:
            raise StopIteration

        self.ilength -= 1

        coco_idx, wiki_idx = self.random_pair_of_indices()

        content_image = self.coco[coco_idx][0]
        if not self.exclude_style:
            style_image = self.wiki[wiki_idx][0]
        else:
            style_image = None

        self._check_data_to_return(style_image, content_image)

        if self.exclude_style:
            return content_image
        else:
            return content_image, style_image