public static function getRelTime($datetime, $datetimeFrom = null)
    {
        $ret = '';
        $dateTime = self::getDateTime($datetime);
        $dateTimeFrom = self::getDateTime($datetimeFrom);
        $dateTimeSameDay = clone $dateTimeFrom;
        $dateTimeSameDay->setTime(0, 0, 0);
        $diffSec = $dateTimeFrom->getTimestamp() - $dateTime->getTimestamp();
        if ($dateTime > $dateTimeFrom) {
            // Future
            $dateTimeTest = clone $dateTimeSameDay;
            if ($dateTime < $dateTimeTest->modify('tomorrow')) {
                $ret = 'Today at '.$dateTime->format('g:ia');
            } elseif ($dateTime < $dateTimeTest->modify('+2 days')) {
                $ret = 'Tomorrow at '.$dateTime->format('g:ia');
            } else {
                $ret = $dateTime->format('F jS');
            }
        } elseif ($diffSec < 60) {
            // within a min
            $ret = 'Just now';
        } elseif ($diffSec < 3600) {
            // within an hour
            $ret = \round(($diffSec)/60) .' min ago';
        } elseif ($diffSec < 3600*6) {
            // within 6 hours
            $hrs = \round(($diffSec)/3600);
            $ret = $hrs.' '.Str::plural($hrs, 'hour').' ago';
        } elseif ($dateTime > $dateTimeSameDay) {             // since midnight so it's today
            $ret = 'Today at '.$dateTime->format('g:ia');
        } elseif ($dateTime->getTimestamp() >= $dateTimeSameDay->getTimestamp() - 86400) {
            $ret = 'Yesterday at '.$dateTime->format('g:ia');
        } elseif ($dateTime->getTimestamp() >= $dateTimeSameDay->getTimestamp() - 86400*7) {
            $ret = $dateTime->format('l \a\t g:ia');
        } elseif ($dateTime->getTimestamp() > \mktime(0, 0, 0, 1, 1)) {// since 1st Jan so it's this year
            $ret = $dateTime->format('F jS');
        } else {                                // last year..
            $ret = $dateTime->format('F jS, Y');
        }
        $ret = \str_replace(' at 12:00am', '', $ret);
        return $ret;
    }