code: async function extractDescriptions(filename, index, response) {
    if (response.textAnnotations.length) {
      const words = extractDescription(response.textAnnotations);
      await index.add(filename, words);
    } else {
      console.log(`${filename} had no discernable text.`);
      await index.setContainsNoText(filename);
    }
  }
docs: Grab the description, and push it into redis.
  @param {string} filename Name of the file being processed
  @param {Index} index The Index object that wraps Redis
  @param {*} response Individual response from the Cloud Vision API
  @returns {Promise<void>}