def _calculate_image_filename(instance, filename):
 return os.path.join(settings.ANNOUNCEMENTS_PHOTO_DIR, (str(uuid.uuid4()) + '.jpg'))

def _calculate_image_filename ( instance , filename ) : return os . path . join ( settings . ANNOUNCEMENTS_PHOTO_DIR , ( str ( uuid . uuid4 ( ) ) + '.jpg' ) )
generate a unique filename for uploaded image .