def _is_valid_cache(self, db_name, table_name):
        # we cache per-table so if the table is there it is valid
        try:
            return self._constraint_cache[db_name][table_name] is not INVALID
        except __HOLE__:
            return False
dataset/ETHPy150Open cloudera/hue/desktop/core/ext-py/South-1.0.2/south/db/generic.py/DatabaseOperations._is_valid_cache