def short_name(self):
        self.assert_valid()
        result = []
        l = self.value
        for v in self._flag_values:
            if (v | l) == l:
                l ^= v
                result.append(self._value_to_name[v])
        if not result:
            if 0 in self._value_to_name:
                return self._value_to_name[0]
            else:
                return ""
        return ",".join(result)