function columnOrderToEnumType(columnOrder) {
  switch (columnOrder) {
    case 'asc': return lf.Order.ASC;
    case 'desc': return lf.Order.DESC;
    default: throw new Error('Invalid column order: ' + columnOrder);
  }
}
@param {string} columnOrder
@return {!lf.Order}
@suppress {missingRequire}