docs: function zipFolder(zip, ffs, root, dir) {
      dir = dir || '';
      let files = ffs.readdirSync(root + (dir ? '/' + dir : ''));
      files.forEach(file => {
          if (['.ts', '.js.map'].some(e => file.endsWith(e))) {
              return;
          }
          let stat = ffs.statSync(root + (dir ? '/' + dir : '') + '/' + file);
          if (stat.isFile()) {
              zipFile(zip, ffs, root, dir, file);
          }
          else if (stat.isDirectory()) {
              zipFolder(zip, ffs, root, dir ? dir + '/' + file : file);
          }
      });
  }