def _register(self, expr, dbname, driver, fn):
        fn_dict = self.reg[dbname]
        if driver in fn_dict:
            raise TypeError(expr % "Multiple functions for expression %r")
        fn_dict[driver] = fn
dataset/ETHPy150Open openstack/oslo.db/oslo_db/sqlalchemy/utils.py/DialectSingleFunctionDispatcher._register/swapped operands of `%`