exslt extension functions in xml_select

[Matt]

Hi,

Just trying out amara, I'm at a loss with regards to how to access the
functions within amara/xslt/exslt/sets.py


import amara

doc = amara.parse("""<xml>
<a>
<b>1</b>
<b>2</b>
<b>3</b>
</a>
<c>
<b>1</b>
<b>5</b>
</c>
</xml>
""")

# How do I can I use the intersection function?
doc.xml_select("set:intersection(//a/b/text(),//c/b/
text())",prefixes={'set':"http://exslt.org/sets"})
# returns 'undefined function'

Many thanks,
Matt