def unpack_rows(self, parameters_metadata, connection):
        """Unpack output or input/output parameters from the stored procedure call result
        :parameters_metadata: a stored procedure parameters metadata
        :returns: parameter values
        """
        values = []
        for param in parameters_metadata:
            # Unpack OUT or INOUT parameters' values
            if param.iotype != parameter_direction.IN:
                values.append( by_type_code[param.datatype].from_resultset(self.payload) )
        yield tuple(values)