How to use the @aws-cdk/aws-autoscaling-hooktargets.FunctionHook function in @aws-cdk/aws-autoscaling-hooktargets

code: lambda.Code.fromInline(fs.readFileSync(path.join(__dirname, 'lambda-source', 'index.py'), { encoding: 'utf-8' })),
      handler: 'index.lambda_handler',
      runtime: lambda.Runtime.PYTHON_3_6,
      // Timeout: some extra margin for additional API calls made by the Lambda,
      // up to a maximum of 15 minutes.
      timeout: cdk.Duration.seconds(Math.min(drainTime.toSeconds() + 10, 900)),
      environment: {
        CLUSTER: props.cluster.clusterName
      }
    });

    // Hook everything up: ASG -> Topic, Topic -> Lambda
    props.autoScalingGroup.addLifecycleHook('DrainHook', {
      lifecycleTransition: autoscaling.LifecycleTransition.INSTANCE_TERMINATING,
      defaultResult: autoscaling.DefaultResult.CONTINUE,
      notificationTarget: new hooks.FunctionHook(fn),
      heartbeatTimeout: drainTime,
    });

    // Describe actions cannot be restricted and restrict the CompleteLifecycleAction to the ASG arn
    // https://docs.aws.amazon.com/autoscaling/ec2/userguide/control-access-using-iam.html
    fn.addToRolePolicy(new iam.PolicyStatement({
      actions: [
        'ec2:DescribeInstances',
        'ec2:DescribeInstanceAttribute',
        'ec2:DescribeInstanceStatus',
        'ec2:DescribeHosts'
      ],
      resources: ['*']
    }));

    // Restrict to the ASG