def clear(self):
all_keys = self._find_keys_raw(settings.THUMBNAIL_KEY_PREFIX)<EOL>if all_keys:<EOL><INDENT>self._delete_raw(*all_keys)<EOL><DEDENT>
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.