How to use the @alfresco/js-api.DiscoveryApi function in @alfresco/js-api

alfrescoApi.login(program.username, program.password).then(() => {
        let discovery = new DiscoveryApi(alfrescoApi);
        discovery.getRepositoryInformation().then(
            (ecmVers) => {
                console.log('ecmVers' + JSON.stringify(ecmVers));
            },
            () => {
                process.exit(1);
            });
    }, () => {
        process.exit(1);

constructor() {
        let alfrescoApi = new AlfrescoApi();
        alfrescoApi.setConfig({
            provider: 'ECM',
            hostEcm: 'http://localhost:3000',
            authType: 'BASIC',
            contextRoot: ''
        });

        let discovery = new DiscoveryApi(alfrescoApi);
        discovery.getRepositoryInformation().then(
            (ecmVers) => {
                console.log('ecmVers' + ecmVers);
            },
            (ecmVers) => {
                console.log('error ecmvers' + ecmVers);
            });
    }
}