docs: def get_upload_path(self, filename):
          ''' Override this in proxy subclass to customize upload path.
              Default upload path is
              :file:`/media/images/<user.id>/<filename>.<ext>`
              or :file:`/media/images/common/<filename>.<ext>` if user is not set.
  
              ``<filename>`` is returned by
              :meth:`~generic_images.models.AbstractAttachedImage.get_file_name`
              method. By default it is probable id of new image (it is
              predicted as it is unknown at this stage).
          '''
          user_folder = str(self.user.pk) if self.user else 'common'
  
          root, ext = os.path.splitext(filename)
          return os.path.join('media', 'images', user_folder,
                              self.get_file_name(filename) + ext)