code: async function getTextFromFiles(index, inputFiles) {
    // Read all of the given files and provide request objects that will be
    // passed to the Cloud Vision API in a batch request.
    const requests = await Promise.all(
      inputFiles.map(async filename => {
        const content = await readFile(filename);
        console.log(` 👉 ${filename}`);
        return {
          image: {
            content: content.toString('base64'),
          },
          features: [{type: 'TEXT_DETECTION'}],
        };
      })
    );
  
    // Make a call to the Vision API to detect text
    const results = await client.batchAnnotateImages({requests});
    const detections = results[0].responses;
    await Promise.all(
      inputFiles.map(async (filename, i) => {
        const response = detections[i];
        if (response.error) {
          console.info(`API Error for ${filename}`, response.error);
          return;
        }
        await extractDescriptions(filename, index, response);
      })
    );
  }
docs: Given a set of image file paths, extract the text and run them through the
  Cloud Vision API.
  @param {Index} index The stateful `Index` Object.
  @param {string[]} inputFiles The list of files to process.
  @returns {Promise<void>}