use of AttributesNSImpl in writing ?

[spinach]

I just can't find a good example for the use of AttributesNSImpl in the
context of writing XML through XMLGenerator. I need to generate XML
that uses several namespaces. The documentation is brief ("understands
attribute names as two-tuples of namespaceURI and localname"), it
appears you have to send it lots of dictionaries full of tuples.
Any clarification on this would be most appreciated.