Cron\Schedule\CrontabSchedule::parseRule PHP Method

    protected function parseRule($rule, $min, $max)
    {
        $result = [];
        foreach (explode(',', $rule) as $value) {
            if (preg_match('/^([0-9]+)-([0-9]+)$/', $value, $r)) {
                $result = array_merge($result, range($r[1], $r[2]));
            } elseif (preg_match('/^\\*\\/([0-9]+)$/', $value, $r)) {
                for ($i = $min; $i <= $max; $i++) {
                    if ($i % $r[1] == 0) {
                        $result[] = $i;
                    }
                }
            } elseif (is_numeric($value)) {
                $result[] = $value;
            }
        }
        return $result;
    }