understanding an xml building library - python openclip

I found this library that supposedly does something I need to do (build XML files for NLEs). It should be a pretty easy to use library that builds an xml. I thought this would work:

import openclip

oc = openclip.OpenClip('testclip.clip')
tracks = openclip.elements.Tracks(None, oc)

# video
vtrack = openclip.elements.Track(None, tracks)
vfeeds = openclip.elements.Feeds(None, vtrack)
vfeed  = openclip.elements.Feed(None, vfeeds)

vfeed.element.set('startTimecode', str( v['sync_point_samples'] ))
vfeed.element.set('sampleRate', str( v['sample_rate'] ))

vspans = openclip.elements.Spans(None, vfeed)
vspan  = openclip.elements.Span(None, vspans)

vspan.element.set('path', v['path'])

# audio
atrack = openclip.elements.Track(None, tracks)
afeeds = openclip.elements.Feeds(None, vtrack)
afeed  = openclip.elements.Feed(None, vfeeds)

afeed.element.set('startTimecode', str( a['sync_point_samples'] ))
afeed.element.set('sampleRate', str( a['sample_rate'] ))

aspans = openclip.elements.Spans(None, vfeed)
aspan  = openclip.elements.Span(None, vspans)

aspan.element.set('path', v['path'])

That's a very rough general idea, I'm trying to basically create a clip with two tracks - one for audio and one for video. I thought this would work like Etree, where you create subelements, and assign them to a parent, gradually building the XML.

But this isn't working. The docs are not very detailed about usage examples, so I'm confused. Tried looking at the source code too, can't find anything useful. Any ideas what am I missing? (p.s. I also tried contacting the developer, he did not answer).