How to use the node-opcua-service-endpoints.UserIdentityTokenType.ANONYMOUS function in node-opcua-service-endpoints

function createAnonymousIdentityToken(endpoint_desc) {
    assert(endpoint_desc instanceof EndpointDescription);
    const userTokenPolicy = findUserTokenPolicy(endpoint_desc, UserIdentityTokenType.ANONYMOUS);
    if (!userTokenPolicy) {
        throw new Error("Cannot find ANONYMOUS user token policy in end point description");
    }
    return new AnonymousIdentityToken({policyId: userTokenPolicy.policyId});
}

function createAnonymousIdentityToken(session) {

    const endpoint_desc = session.endpoint;
    assert(endpoint_desc instanceof EndpointDescription);

    const userTokenPolicy = findUserTokenPolicy(endpoint_desc, UserIdentityTokenType.ANONYMOUS);
    if (!userTokenPolicy) {
        throw new Error("Cannot find ANONYMOUS user token policy in end point description");
    }
    return new AnonymousIdentityToken({policyId: userTokenPolicy.policyId});
}