src/Marando/AstroDate/Traits/FormatTrait.php
private function formatZ(&$str) {
    if (strstr($str, '%Z'))
      $str = str_replace('%Z', $this->timezone->offset * 3600, $str);
  }
private function formatZ(&$str) {
    if (strstr($str, '%Z'))
      $str = str_replace('%Z', $this->timezone->offset * 3600, $str);
  }
Timezone offset in seconds
@param type $str