在php中创建具有相同命名空间的多个xml节点

I have the following code

我有以下代码

    $dom = new DOMDocument('1.0', 'utf-8');        
    $headerNS = $dom->createElementNS('https://somenamespace', 'ttauth:authHeader');
    $accesuser = $dom->createElementNS('https://somenamespace', 'ttauth:Accessuser','aassdd');
    $accesscode = $dom->createElementNS('https://somenamespace', 'ttauth:Accesscode','aassdd');
    $headerNS->appendChild($accesuser);
    $headerNS->appendChild($accesscode);

    echo "<pre>";
    echo ($dom->saveXML($headerNS));
    echo "</pre>";
    $dom