public function timespan($time = null, $timezone = null)
    {
        // Get translator
        $lang = $this->getTranslator();

        // Create Date instance if needed
        if (!$time instanceof static) {
            $time = Date::parse($time, $timezone);
        }

        $units = [
            'y' => 'year',
            'm' => 'month',
            'w' => 'week',
            'd' => 'day',
            'h' => 'hour',
            'i' => 'minute',
            's' => 'second',
        ];

        // Get DateInterval and cast to array
        $interval = (array) $this->diff($time);

        // Get weeks
        $interval['w'] = (int) ($interval['d'] / 7);
        $interval['d'] = $interval['d'] % 7;

        // Get ready to build
        $str = [];

        // Loop all units and build string
        foreach ($units as $k => $unit) {
            if ($interval[$k]) {
                $str[] = $lang->transChoice($unit, $interval[$k], [':count' => $interval[$k]]);
            }
        }

        return implode(', ', $str);
    }