Quarter/year custom formatter (datetime)

/**
* Implements hook_field_formatter_view().
*/
function MYMODULE_field_formatter_view($obj_type, $object, $field, $instance, $langcode, $items, $display) {
  $element = array();
  switch ($display['type']) {
    case 'FORMATTER_NAME':
      foreach ($items as $delta => $item) {
        if ($item['value']) {
          $date = new DateObject($item['value']);
          $quarter = ceil(date_format_date($date, 'custom', 'n', $langcode = NULL)/3);
          $year = date_format_date($date, 'custom', 'Y', $langcode = NULL);
          $element[$delta] = array(
           '#markup' => t('Quarter @quarter, @year', array('@quarter' => $quarter, '@year' => $year)),
          );
        }
      }
    break;
  }
  return $element;
}