def _sql_sorts(self):
        sql_sorts = []
        for sort in reversed(self.sorts):
            if not sort.order_clause() is None:
                sql_sorts.append(sort)
            else:
                break
        sql_sorts.reverse()
        return sql_sorts
Return the list of sub-sorts for which we can be (at least
dataset/ETHPy150Open beetbox/beets/beets/dbcore/query.py/MultipleSort._sql_sorts