src/Debug/Output/Base.php
protected function checkTimestamp($val)
    {
        $secs = 86400 * 90; // 90 days worth o seconds
        $tsNow = \time();
        if ($val > $tsNow - $secs && $val < $tsNow + $secs) {
            return \date('Y-m-d H:i:s', $val);
        }
        return false;
    }
protected function checkTimestamp($val)
    {
        $secs = 86400 * 90; // 90 days worth o seconds
        $tsNow = \time();
        if ($val > $tsNow - $secs && $val < $tsNow + $secs) {
            return \date('Y-m-d H:i:s', $val);
        }
        return false;
    }
Is value a timestamp?

@param mixed $val value to check

@return string|false