How to QuickSort a map?

Sean Durkin wrote:

> XPath 3 can now implement QuickSort in 3 lines of code.

Sean (or anyone) would you show how to implement the QuickSort please?

That is, would you replace the ??? in the below function with the code
please?

---------------------------------------------------------------------
    <xsl:function name="f:sort-map" as="map(xs:anyAtomicType, item()*)">
        <xsl:param name="m" as="map(xs:anyAtomicType, item()*)" />

        ???

    </xsl:function>
---------------------------------------------------------------------

/Roger