code: def thumbnail(self, img_url, size, crop=None, bg=None, quality=85,
                    storage_type=None, bucket_name=None):
          
  
          width, height = [int(x) for x in size.split('x')]
          thumb_size = (width, height)
          url_path, img_name = os.path.split(img_url)
          name, fm = os.path.splitext(img_name)
  
          miniature = self._get_name(name, fm, size, crop, bg, quality)
  
          original_filename = os.path.join(self.app.config['MEDIA_FOLDER'], url_path, img_name)
          thumb_filename = os.path.join(self.app.config['MEDIA_THUMBNAIL_FOLDER'], url_path, miniature)
  
          thumb_url = os.path.join(self.app.config['MEDIA_THUMBNAIL_URL'], url_path, miniature)
  
          if not (storage_type and bucket_name):
              return self._thumbnail_local(original_filename,
                                           thumb_filename,
                                           thumb_size,
                                           thumb_url,
                                           crop=crop,
                                           bg=bg,
                                           quality=quality)
          else:
              if storage_type != 's3':
                  raise ValueError('Storage type "%s" is invalid, the only supported storage type (apart from default local storage) is s3.' % storage_type)
  
              return self._thumbnail_s3(original_filename,
                                        thumb_filename,
                                        thumb_size,
                                        thumb_url,
                                        bucket_name,
                                        crop=crop,
                                        bg=bg,
                                        quality=quality)
docs: :param img_url: url img - '/assets/media/summer.jpg'
          :param size: size return thumb - '100x100'
          :param crop: crop return thumb - 'fit' or None
          :param bg: tuple color or None - (255, 255, 255, 0)
          :param quality: JPEG quality 1-100
          :param storage_type: either 's3' or None
          :param bucket_name: s3 bucket name
          :return: :thumb_url: