/**
* Gets the date as an ISO 8601 string. IETF RFC 3339 defines the ISO 8601 format
* and it can be found at the IETF Web site.
*
* @param boolean $local True to return the date string in the local time zone, false to return it in GMT.
*
* @return string The date string in ISO 8601 format.
*
* @link http://www.ietf.org/rfc/rfc3339.txt
* @since 1.7.0
*/
public function toISO8601($local = false)
{
return $this->format(\DateTimeInterface::RFC3339, $local, false);
}