code: function processDataItems(items) {
      var processedItems = []
        ;
  
      // TODO: do stemming here
      items.forEach(function (item, i) {
        processedItems[i] = processString(item);
      });
      return processedItems;
    }
docs: This is terribly named. Process the array of strings into an
  array of arrays of words, with them stemmed, etc.