How to use the @now/build-utils/fs/download.js function in @now/build-utils

async function downloadInstallAndBundle(
  { files, entrypoint, workPath },
  { npmArguments = [] } = {}
) {
  const userPath = path.join(workPath, 'user')
  const nccPath = path.join(workPath, 'ncc')
  const ftsPath = path.join(workPath, 'fts')

  console.log()
  console.log('downloading user files...')
  const downloadedFiles = await download(files, userPath)

  console.log()
  console.log("installing dependencies for user's code...")
  const entrypointFsDirname = path.join(userPath, path.dirname(entrypoint))
  await runNpmInstall(entrypointFsDirname, npmArguments)

  console.log('writing ncc package.json...')
  fs.outputJsonSync(path.join(nccPath, 'package.json'), {
    dependencies: {
      '@zeit/ncc': '0.11.0',
      typescript: '3.2.4'
    }
  })

  console.log()
  console.log('installing dependencies for ncc...')

}) => {
    console.log('entrypoint ', entrypoint);
    validateEntrypoint(entrypoint);

    console.log('downloading user files...');
    const entryDirectory = path.dirname(entrypoint);
    const filesOnlyEntryDirectory = includeOnlyEntryDirectory(
        files,
        entryDirectory,
    );
    const filesWithEntryDirectoryRoot = moveEntryDirectoryToRoot(
        filesOnlyEntryDirectory,
        entryDirectory,
    );
    const filesWithoutLockfiles = excludeLockFiles(filesWithEntryDirectoryRoot);
    const downloadedFiles = await download(filesWithoutLockfiles, workPath);

    console.log('normalizing package.json');
    const packageJson = normalizePackageJson(
        await readPackageJson(downloadedFiles),
    );
    console.log('normalized package.json result: ', packageJson);
    await writePackageJson(workPath, packageJson);

    if (process.env.NPM_AUTH_TOKEN) {
        console.log('found NPM_AUTH_TOKEN in environment, creating .npmrc');
        await writeNpmRc(workPath, process.env.NPM_AUTH_TOKEN);
    }

    console.log('running npm install...');
    await runNpmInstall(workPath, ['--prefer-offline']);
    console.log('running user script...');

workPath,
}) => {
    console.log('downloading user files...');
    const entryDirectory = path.dirname(entrypoint);
    const filesOnlyEntryDirectory = includeOnlyEntryDirectory(
        files,
        entryDirectory,
    );
    const filesWithEntryDirectoryRoot = moveEntryDirectoryToRoot(
        filesOnlyEntryDirectory,
        entryDirectory,
    );
    const filesWithoutLockfiles = excludeLockFiles(filesWithEntryDirectoryRoot);
    await download(filesWithoutLockfiles, workPath);
    await download(await glob('.nuxt/**', workPath), cachePath);
    await download(await glob('node_modules/**', workPath), cachePath);

    console.log('.nuxt folder contents', await glob('.nuxt/**', cachePath));
    console.log(
        '.cache folder contents',
        await glob('node_modules/.cache/**', cachePath),
    );

    console.log('running npm install...');
    await runNpmInstall(cachePath);

    return {
        ...(await glob('.nuxt/server/index.spa.html', cachePath)),
        ...(await glob('.nuxt/server/index.ssr.html', cachePath)),
        ...(await glob('.nuxt/server/vue-ssr-client-manifest.json', cachePath)),
        ...(await glob('.nuxt/server/server-bundle.json', cachePath)),
        ...(await glob('node_modules/**', cachePath)),

async function downloadFiles(files, entrypoint, workPath) {
  console.log('Downloading files...');
  const downloadedFiles = await download(files, workPath);
  const entryPath = downloadedFiles[entrypoint].fsPath;

  return { files: downloadedFiles, entryPath };
}