Python lxml xpath XPathEvalError: Invalid expression — why?

[cengiz802]

I'm trying to parse an SVG document with \[code\]lxml\[/code\]. Here's my code:\[code\]nsmap = { 'svg': 'http://www.w3.org/2000/svg', 'xlink': 'http://www.w3.org/1999/xlink',}root = etree.XML(svg)# this works (finds the element with the given ID)root.xpath('./svg:g/svg:g/svg:g[@id="route_1_edge"]', namespaces=nsmap)# this yields "XPathEvalError: Invalid expression"root.xpath('./svg:g/svg:g/svg:g[fn:startswith(@id,"route_1")]', namespaces=nsmap)\[/code\]Anyone know why the first one works and the second doesn't? If I change the third \[code\]svg:g\[/code\] to \[code\]svg:text\[/code\] I don't get an exception, so it seems to be something to do with the \[code\]g\[/code\] element in particular that it doesn't like, though, again, the simple \[code\]g[@id="foo"]\[/code\] search works fine.