code: function defaultFilenameModifier (fileInfo, version) {
    if (fileInfo.dest.endsWith('index.um')) {
      return fileInfo.clone({
        dest: fileInfo.dest.replace('index.um', version) + '/' + 'index.um'
      })
    } else {
      return fileInfo.clone({
        dest: fileInfo.dest.replace('.um', '') + '/' + version + '.um'
      })
    }
  }
docs: /* The default function used to rename files as they pass through the version transform