How to use the @aws-cdk/core.Token function in @aws-cdk/core

constructor(parent: Construct, name: string, props: BucketProps = {}) {
        super(parent, name);

        validateBucketName(props && props.bucketName);

        const { bucketEncryption, encryptionKey } = this.parseEncryption(props);

        const resource = new cloudformation.BucketResource(this, 'Resource', {
            bucketName: props && props.bucketName,
            bucketEncryption,
            versioningConfiguration: props.versioned ? { status: 'Enabled' } : undefined,
            lifecycleConfiguration: new Token(() => this.parseLifecycleConfiguration()),
        });

        applyRemovalPolicy(resource, props.removalPolicy);

        this.versioned = props.versioned;
        this.policy = props.policy;
        this.encryptionKey = encryptionKey;
        this.bucketArn = resource.bucketArn;
        this.bucketName = resource.ref;
        this.domainName = resource.bucketDomainName;
        this.dualstackDomainName = resource.bucketDualStackDomainName;

        // Add all lifecycle rules
        (props.lifecycleRules || []).forEach(this.addLifecycleRule.bind(this));
    }

if (props.allowAllOutbound !== false) {
            this.connections.allowTo(new AnyIPv4(), new AllConnections(), 'Outbound traffic allowed by default');
        }

        this.role = new iam.Role(this, 'InstanceRole', {
            assumedBy: new ServicePrincipal('ec2.amazonaws.com')
        });

        const iamProfile = new iam.cloudformation.InstanceProfileResource(this, 'InstanceProfile', {
            roles: [ this.role.roleName ]
        });

        // use delayed evaluation
        const machineImage = props.machineImage.getImage(this);
        const userDataToken = new Token(() => new FnBase64((machineImage.os.createUserData(this.userDataLines))));

        const launchConfig = new autoscaling.cloudformation.LaunchConfigurationResource(this, 'LaunchConfig', {
            imageId: machineImage.imageId,
            keyName: props.keyName,
            instanceType: props.instanceType.toString(),
            securityGroups: [this.securityGroup.securityGroupId],
            iamInstanceProfile: iamProfile.ref,
            userData: userDataToken
        });

        launchConfig.addDependency(this.role);

        const minSize = props.minSize || 1;
        const maxSize = props.maxSize || 1;
        const desiredCapacity = props.desiredCapacity || 1;

constructor(parent: Construct, name: string, props: PrivateHostedZoneProps) {
        super(parent, name);

        validateZoneName(props.zoneName);

        const hostedZone = new cloudformation.HostedZoneResource(this, 'Resource', {
            vpcs: new Token(() => this.vpcs ? this.vpcs : undefined),
            ...determineHostedZoneProps(props)
        });

        this.hostedZoneId = hostedZone.ref;
        this.zoneName = props.zoneName;

        this.addVpc(props.vpc);
    }

})],
        });

        for (const statement of (props.initialPolicy || [])) {
            this.role.addToPolicy(statement);
        }

        const resource = new cloudformation.FunctionResource(this, 'Resource', {
            functionName: props.functionName,
            description: props.description,
            code: props.code.toJSON(props.runtime),
            handler: props.handler,
            timeout: props.timeout,
            runtime: props.runtime.name,
            role: this.role.roleArn,
            environment: new Token(() => this.renderEnvironment()),
            memorySize: props.memorySize,
        });

        resource.addDependency(this.role);

        this.functionName = resource.ref;
        this.functionArn = resource.functionArn;
    }

constructor(parent: Construct, name: string, props: SecurityGroupProps) {
        super(parent, name, { securityGroupId: new Token(() => this.securityGroup.securityGroupId) });

        const groupDescription = props.description || this.path;

        this.securityGroup = new cloudformation.SecurityGroupResource(this, 'Resource', {
            groupName: props.groupName,
            groupDescription,
            securityGroupIngress: new Token(() => this.directIngressRules),
            securityGroupEgress: new Token(() => this.directEgressRules),
            vpcId: props.vpc.vpcId,
        });

        this.groupName = this.securityGroup.ref;
        this.vpcId = this.securityGroup.securityGroupVpcId;
    }

constructor(parent: Construct, name: string, props: EventRuleProps = { }) {
        super(parent, name);

        const resource = new cloudformation.RuleResource(this, 'Resource', {
            description: props.description,
            state: props.enabled == null ? 'ENABLED' : (props.enabled ? 'ENABLED' : 'DISABLED'),
            scheduleExpression: new Token(() => this.scheduleExpression),
            eventPattern: new Token(() => this.renderEventPattern()),
            targets: new Token(() => this.renderTargets())
        });

        this.ruleArn = resource.ruleArn;

        this.addEventPattern(props.eventPattern);
        this.scheduleExpression = props.scheduleExpression;

        for (const target of props.targets || []) {
            this.addTarget(target);
        }
    }

iamInstanceProfile: iamProfile.ref,
            userData: userDataToken
        });

        launchConfig.addDependency(this.role);

        const minSize = props.minSize || 1;
        const maxSize = props.maxSize || 1;
        const desiredCapacity = props.desiredCapacity || 1;

        const asgProps: autoscaling.cloudformation.AutoScalingGroupResourceProps = {
            minSize: minSize.toString(),
            maxSize: maxSize.toString(),
            desiredCapacity: desiredCapacity.toString(),
            launchConfigurationName: launchConfig.ref,
            loadBalancerNames: new Token(() => this.loadBalancerNames),
        };

        if (props.notificationsTopic) {
            asgProps.notificationConfigurations = [];
            asgProps.notificationConfigurations.push({
                topicArn: props.notificationsTopic.ref,
                notificationTypes: [
                    "autoscaling:EC2_INSTANCE_LAUNCH",
                    "autoscaling:EC2_INSTANCE_LAUNCH_ERROR",
                    "autoscaling:EC2_INSTANCE_TERMINATE",
                    "autoscaling:EC2_INSTANCE_TERMINATE_ERROR"
                ],
            });
        }

        const subnets = props.vpc.subnets(props.vpcPlacement);

constructor(parent: Construct, name: string, props: SecurityGroupProps) {
        super(parent, name, { securityGroupId: new Token(() => this.securityGroup.securityGroupId) });

        const groupDescription = props.description || this.path;

        this.securityGroup = new cloudformation.SecurityGroupResource(this, 'Resource', {
            groupName: props.groupName,
            groupDescription,
            securityGroupIngress: new Token(() => this.directIngressRules),
            securityGroupEgress: new Token(() => this.directEgressRules),
            vpcId: props.vpc.vpcId,
        });

        this.groupName = this.securityGroup.ref;
        this.vpcId = this.securityGroup.securityGroupVpcId;
    }

constructor(parent: Construct, name: string, props: EventRuleProps = { }) {
        super(parent, name);

        const resource = new cloudformation.RuleResource(this, 'Resource', {
            description: props.description,
            state: props.enabled == null ? 'ENABLED' : (props.enabled ? 'ENABLED' : 'DISABLED'),
            scheduleExpression: new Token(() => this.scheduleExpression),
            eventPattern: new Token(() => this.renderEventPattern()),
            targets: new Token(() => this.renderTargets())
        });

        this.ruleArn = resource.ruleArn;

        this.addEventPattern(props.eventPattern);
        this.scheduleExpression = props.scheduleExpression;

        for (const target of props.targets || []) {
            this.addTarget(target);
        }
    }

export function undefinedIfEmpty(f: () => T[]): Token {
    return new Token(() => {
        const array = f();
        return (array && array.length > 0) ? array : undefined;
    });
}