code: function(formId, fileSizes) {
          var totalFileSizes = 0;
  
          for (var fileSizeIdx = 0; fileSizeIdx < fileSizes.length ; fileSizeIdx++) {
            totalFileSizes += fileSizes[fileSizeIdx];
          }
  
          return totalFileSizes;
        }
docs: NOTE: this function executes in MongoDB rather than Node.js Function to sum up all of the file sizes for each submission