    # File lib/fog/aws/models/rds/server.rb, line 81
            def modify(immediately, options)
              options[:security_group_names] ||= options['DBSecurityGroups']
              params = self.class.new(options).attributes_to_params
              data = service.modify_db_instance(id, immediately, params)
              merge_attributes(data.body['ModifyDBInstanceResult']['DBInstance'])
              true
            end