public function diff($date = 'now')
	{
		if ($date instanceof static)
			return $this->date->diff($date->date);
		else if ($date instanceof \DateTime)
			return $this->date->diff($date);
		else if (is_string($date))
			return $this->date->diff(new \DateTime($date, self::$utc));
	//	return is_string($date) ? (new \DateTime($date, self::$utc))->diff($this->date)->days : $date->diff($this->date)->days;
	}