How to use the node-opcua-service-endpoints.ApplicationType.ClientAndServer function in node-opcua-service-endpoints

exports.makeEndPoint = function () {

    var data = {
        endpointUrl: "toto",

        server: {

            applicationUri: "OPCUA  node-js",
            productUri: "some product uri",
            applicationName: {text: "Localised application name"},
            applicationType: ApplicationType.ClientAndServer,
            gatewayServerUri: "gatewayServerUri",
            discoveryProfileUri: "discoveryProfileUri",
            discoveryUrls: [
                "discoveryUrls1",
                "discoveryUrls2",
                "discoveryUrls3",
                "discoveryUrls4",
                "discoveryUrls5"
            ]
        },

        serverCertificate: Buffer.alloc(256),

        securityMode: MessageSecurityMode.None,

        securityPolicyUri: "http://opcfoundation.org/UA/SecurityPolicy#Basic128Rsa15",

function _isValidServerType(serverType: ApplicationType): boolean {

    switch (serverType) {
        case ApplicationType.Client:
            return false;
        case ApplicationType.Server:
        case ApplicationType.ClientAndServer:
        case ApplicationType.DiscoveryServer:
            return true;
    }
    return false;
}