lxml question -- creating an etree.Element attribute with ':' in the name

[Roy Smith]

I can create an Element with a 'foo' attribute by doing:

etree.Element('my_node_name', foo="spam")

But, how do I handle something like:

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance", since "xmlns:xsi" isn't a valid python identifier?

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Roy Smith
roy at panix.com