docstr: Returns a list of filenames for each slice.
  
  Returns:
      filenames: a list of filenames as str
code: def filenames(self) -> List[int]:
      """Returns a list of filenames for each slice.
  
      Returns:
          filenames: a list of filenames as str
      """
      filenames = []
      for sliced_image in self._sliced_image_list:
          filenames.append(sliced_image.coco_image.file_name)
      return filenames
  
imports: import concurrent.futures
  import logging
  import os
  import time
  from pathlib import Path
  from typing import Dict, List, Optional, Sequence, Tuple, Union
  import numpy
  from PIL import Image
  from shapely.errors import TopologicalError
  from tqdm import tqdm
  from sahi.annotation import BoundingBox, Mask
  from sahi.utils.coco import Coco, CocoAnnotation, CocoImage, create_coco_dict
  from sahi.utils.cv import IMAGE_EXTENSIONS_LOSSLESS, IMAGE_EXTENSIONS_LOSSY, read_image_as_pil
  from sahi.utils.file import load_json, save_json
label_desc: Use image node_id 7 for calling the SliceImageResult obj's underlying member method code with example usage: obj.filenames() and returns: filenames