advene.model.backends.exceptions.PackageInUse:
I am raised whenever an attempt is made to bind a Package instance
to a backend already bound, or to create an existing (bound or not)
Package.
advene.model.parsers.base_xml.Stream:
Wrap the result of iterparse:
* start-ns and end-ns are interpreted, (prefix, uri) pairs being pushed
and popped accordingly in attribute `namespaces`
* start and end events are accessible through the `event` and `elem`
advene.model.events.WithEventsMixin:
This mixin class assumes that the mixed-in class will provide a
`_make_event_delegate` method returning an instance of the
appropriate subclass of EventDelegate.