QXmlStreamWriter: Be able to have a prefix before a namespace in an element

QXmlStreamWriter: Be able to have a prefix before a namespace in an element, for example, SOAP has something like:

<?xml version="1.0"?>
<soap:Envelope
xmlns:soap="http://www.w3.org/2001/12/soap-envelope"
soap:encodingStyle="http://www.w3.org/2001/12/soap-encoding">
...
Message information goes here
...
</soap:Envelope>

However xmlns:soap is the namespace here and the soap:Envelope needs to come first, therefore it would be nice if it was possible to use QXmlStreamWriter to write out this sort of XML.