Why doesn't xpath work when processing an XHTML document with lxml (in python)?

Question

I am testing against the following test document:

Answer 1

The problem is the namespaces. When parsed as XML, the img tag is in the http://www.w3.org/1999/xhtml namespace since that is the default namespace for the element. You are asking for the img tag in no namespace.

Try this:

>>> tree.getroot().xpath(
...     "//xhtml:img", 
...     namespaces={'xhtml':'http://www.w3.org/1999/xhtml'}
...     )
[]