TYPO3 Core

psoudo code:

$lines = 'array(' . LF;
        $level ++;

// determine if keys are int from 0 to n, without gaps, then $isIntKey = TRUE

foreach ($array as $key => $value) {
                // if isIntKey
            $lines = '';
            else $lines .= str_repeat(TAB, $level) . '\'' . $key . '\' => ';