docs: def get_image_format(filename):
      """Get the image format."""
      image = None
      bad_image = 1
      image_format = NONE_FORMAT
      sequenced = False
      try:
          bad_image = Image.open(filename).verify()
          image = Image.open(filename)
          image_format = image.format
          sequenced = _is_image_sequenced(image)
      except (OSError, IOError, AttributeError):
          pass
  
      if sequenced:
          image_format = gif.SEQUENCED_TEMPLATE.format(image_format)
      elif image is None or bad_image or image_format == NONE_FORMAT:
          image_format = ERROR_FORMAT
          comic_format = comic.get_comic_format(filename)
          if comic_format:
              image_format = comic_format
          if (Settings.verbose > 1) and image_format == ERROR_FORMAT and \
                  (not Settings.list_only):
              print(filename, "doesn't look like an image or comic archive.")
      return image_format