code: function arrayize(values) {
    // return empty array if values is empty
    if (typeof values === 'undefined' || values === null ) {
      return [];
    }
    // return array of values, converting to array if necessary
    return util.isArray(values) ? values : [values];
  }
docs: Make sure to always return an array. If passed undefined or null,
  return an empty array. If an array is passed, then return the
  array. If passed anything else, return an array containing
  that value.
  
  @param {*} values Array of values or a single value
  @return {Array} Array of values