code: function main(argv, callback) {
    if (!callback) {
      callback = argv;
      argv = null;
    }
    console.log('Retrieving root certs from: %s', certUrl);
    return getRootCerts(function(err, certs) {
      if (err) {
        console.log('Error', err);
        return callback();
      }
      var file = path.resolve(__dirname, 'lib', 'rootcerts.json');
      return fs.writeFile(file, certs, function(err) {
        if (err) return callback(err);
        console.log('Root cert code generated at: %s.', file);
        return callback();
      });
    });
  }
docs: Execute