Including a saxon:function

 I've written a saxon:function that I want to include in several different
stylesheets. The function works when I physically add it to my stylesheet like
so:

<xsl:stylesheet ...>

<xsl:include href="a"/>
<xsl:include href="b"/>

<xsl:template ...

<saxon:function name="func:c">
 ...
 <saxon:return ...>
</saxon:function>

</xsl:stylesheet>


 But I haven't been able to work out how to include the function if it's
externalized in another file.
 Does anyone have a snippet of code that illustrates how I can include it or
reference it as a separate file.

Thanks,
 Craig Sampson