# File lib/fog/aws/requests/rds/modify_db_instance.rb, line 30
        def modify_db_instance(db_name, apply_immediately, options={})
          if security_groups = options.delete('DBSecurityGroups')
            options.merge!(Fog::AWS.indexed_param('DBSecurityGroups.member.%d', [*security_groups]))
          end

          if vpc_security_groups = options.delete('VpcSecurityGroups')
            options.merge!(Fog::AWS.indexed_param('VpcSecurityGroupIds.member.%d', [*vpc_security_groups]))
          end

          request({
            'Action'               => 'ModifyDBInstance',
            'DBInstanceIdentifier' => db_name,
            'ApplyImmediately'     => apply_immediately,
            :parser                => Fog::Parsers::AWS::RDS::ModifyDBInstance.new
          }.merge(options))
        end