public function daily($hour = 0, $minute = 0)
    {
        if (is_string($hour)) {
            $parts = explode(':', $hour);
            $hour = $parts[0];
            $minute = isset($parts[1]) ? $parts[1] : '0';
        }

        $c = $this->validateCronSequence($minute, $hour);

        return $this->at("{$c['minute']} {$c['hour']} * * *");
    }