How to use the cloudform.Fn.ImportValue function in cloudform

// },
        Origins: [
            {
                Id: "s3Origin",
                DomainName: Fn.GetAtt("ClientBucket", "DomainName"),
                S3OriginConfig: {
                    OriginAccessIdentity: Fn.Join("/", [
                        "origin-access-identity/cloudfront",
                        Fn.Ref("ClientOriginAccessIdentity")
                    ])
                }
            }
        ],
        PriceClass: "PriceClass_100", // PriceClass_100 | PriceClass_200 | PriceClass_All
        ViewerCertificate: {
            AcmCertificateArn: Fn.ImportValue(
                `${pascalCaseDomainName(config.ROOT_DOMAIN)}Certificate`
            ),
            MinimumProtocolVersion: "TLSv1.1_2016",
            SslSupportMethod: "sni-only"
        }
    }
}).dependsOn(["ClientBucket", "ClientOriginAccessIdentity"]);

import { ApiGateway, Fn } from "cloudform";

export const DomainName = new ApiGateway.DomainName({
    DomainName: Fn.Join(".", [Fn.Ref("SubDomain"), Fn.ImportValue("RootDomain")]),
    CertificateArn: Fn.ImportValue("Certificate")
}).dependsOn("ApiGateway");

import { Cognito, Fn } from "cloudform";

export const IdentityPoolRoleAttachment = new Cognito.IdentityPoolRoleAttachment({
    IdentityPoolId: Fn.ImportValue("IdentityPoolId"),
    Roles: {
        authenticated: Fn.GetAtt("CustomerRole", "Arn"),
        unauthenticated: Fn.GetAtt("UnauthenticatedUserRole", "Arn")
    }
});

import { ApiGateway, Fn } from "cloudform";

export const DomainName = new ApiGateway.DomainName({
    DomainName: Fn.Join(".", [Fn.Ref("SubDomain"), Fn.ImportValue("RootDomain")]),
    CertificateArn: Fn.ImportValue("Certificate")
}).dependsOn("ApiGateway");

import { IAM, Fn } from "cloudform";

export const UnauthenticatedUserRole = new IAM.Role({
    RoleName: "passninja-unauthenticated-user-role",
    AssumeRolePolicyDocument: {
        Version: "2012-10-17",
        Statement: [
            {
                Effect: "Allow",
                Principal: {
                    Federated: "cognito-identity.amazonaws.com"
                },
                Action: "sts:AssumeRoleWithWebIdentity",
                Condition: {
                    StringEquals: {
                        "cognito-identity.amazonaws.com:aud": Fn.ImportValue("IdentityPoolId")
                    },
                    "ForAnyValue:StringLike": {
                        "cognito-identity.amazonaws.com:amr": "unauthenticated"
                    }
                }
            }
        ]
    }
});

import { Route53, Fn } from "cloudform";
import { config } from "../../config";
import { pascalCaseDomainName } from "../../lib";

export const ClientRecordSet = new Route53.RecordSet({
    Name: Fn.Join(".", [Fn.Ref("SubDomain"), config.ROOT_DOMAIN]),
    Type: "A",
    HostedZoneId: Fn.ImportValue(`${pascalCaseDomainName(config.ROOT_DOMAIN)}HostedZone`),
    AliasTarget: {
        DNSName: Fn.GetAtt("ClientDistribution", "DomainName"),
        HostedZoneId: "Z2FDTNDATAQYW2"
    }
}).dependsOn("ClientDistribution");

import { Route53, Fn } from "cloudform";
import { config } from "../../config";
import { pascalCaseDomainName } from "../../lib";

export const ServerRecordSet = new Route53.RecordSet({
    Name: Fn.Join(".", [Fn.Ref("SubDomain"), config.ROOT_DOMAIN]),
    Type: "A",
    HostedZoneId: Fn.ImportValue(`${pascalCaseDomainName(config.ROOT_DOMAIN)}HostedZone`),
    AliasTarget: {
        DNSName: Fn.GetAtt("DomainName", "DistributionDomainName"),
        HostedZoneId: Fn.GetAtt("DomainName", "DistributionHostedZoneId")
    }
}).dependsOn("DomainName");

import { IAM, Fn } from "cloudform";

export const CustomerRole = new IAM.Role({
    RoleName: "passninja-customer-role",
    AssumeRolePolicyDocument: {
        Version: "2012-10-17",
        Statement: [
            {
                Effect: "Allow",
                Principal: {
                    Federated: "cognito-identity.amazonaws.com"
                },
                Action: "sts:AssumeRoleWithWebIdentity",
                Condition: {
                    StringEquals: {
                        "cognito-identity.amazonaws.com:aud": Fn.ImportValue("IdentityPoolId")
                    },
                    "ForAnyValue:StringLike": {
                        "cognito-identity.amazonaws.com:amr": "authenticated"
                    }
                }
            }
        ]
    }
});