code: function(next) {
          if (!extension[type] || typeof extension[type] !== 'function') {
            return next();
          }
  
          // Invoke type hook implemetation.
          extension[type](result, function(error, newItems) {
            if (error) {
              return next(error);
            }
  
            utils.extend(result, newItems || {});
  
            next();
          });
        }
docs: The callback that will receive and process.