如何将数组转换为XML，并将整数索引转换为超级节点

<?php
function arrayToXml($array, $xml = null) {
    if ($xml === null) {
        $xml = new SimpleXMLElement('<root/>');
    }
    foreach ($array as $key => $value) {
        if (is_array($value)) {
            if (is_numeric($key)) {
                $key = 'item';
            }
            $subnode = $xml->addChild($key);
            arrayToXml($value, $subnode);
        } else {
            $xml->addChild($key, htmlspecialchars($value));
        }
    }
    return $xml->asXML();
}

$array = array(
    'name' => 'John Doe',
    'age' => 30,
    'languages' => array(
        'language' => 'PHP',
        'level' => 'advanced'
    ),
    'hobbies' => array(
        'hobby' => array(
            'name' => 'reading',
            'type' => 'indoor'
        )
    )
);

$xmlString = arrayToXml($array);
echo $xmlString;
?>

<root>
    <name>John Doe</name>
    <age>30</age>
    <languages>
        <language>PHP</language>
        <level>advanced</level>
    </languages>
    <hobbies>
        <hobby>
            <name>reading</name>
            <type>indoor</type>
        </hobby>
    </hobbies>
</root>