code: def clear(self):
          
          all_keys = self._find_keys_raw(settings.THUMBNAIL_KEY_PREFIX)
          if all_keys:
              self._delete_raw(*all_keys)
docs: Brutely clears the key value store for keys with THUMBNAIL_KEY_PREFIX
          prefix. Use this in emergency situations. Normally you would probably
          want to use the ``cleanup`` method instead.