How to use the hops-config.host function in hops-config

function defaultCallback(error) {
  if (error) {
    console.error(error.stack.toString());
  } else {
    console.log(
      'hops: Server listening at ' +
        url.format({
          protocol: hopsConfig.https ? 'https' : 'http',
          hostname:
            hopsConfig.host === '0.0.0.0' ? 'localhost' : hopsConfig.host,
          port: hopsConfig.port,
          pathname: hopsConfig.basePath,
        })
    );
  }
}