code: def _generate_examples(self, archive_paths, objects_getter, bboxes_getter,
                           prefixes=None):
      
      trainable_classes = set(
          self.info.features['objects_trainable']['label'].names)
      for i, archive_path in enumerate(archive_paths):
        prefix = prefixes[i] if prefixes else None
        objects = objects_getter(prefix)
        bboxes = bboxes_getter(prefix)
        logging.info('Opening archive %s ...', archive_path)
        archive = tfds.download.iter_archive(
            archive_path, tfds.download.ExtractMethod.TAR_STREAM)
        for fpath, fobj in archive:
          fname = os.path.basename(fpath)
          image_id = int(os.path.splitext(fname)[0], 16)
          image_objects = [obj._asdict() for obj in objects.get(image_id, [])]
          image_bboxes = [bbox._asdict() for bbox in bboxes.get(image_id, [])]
          image_objects_trainable = [
              obj for obj in image_objects if obj['label'] in trainable_classes
          ]
          yield {
              'image': _resize_image_if_necessary(
                  fobj, target_pixels=self.builder_config.target_pixels),
              'image/filename': fname,
              'objects': image_objects,
              'objects_trainable': image_objects_trainable,
              'bobjects': image_bboxes,
          }
docs: Yields examples.