dedupe a jspf playlist

gistfile1.py

import json
f = open('playlist.json', 'r')
playlist = json.loads(f.read())
f.close()
tracks = []
track_ids = []
for track in playlist['playlist']['track']:
    track_id = track['identifier'][0]
    if track_id not in track_ids:
        tracks.append(track)
    track_ids.append(track_id)
playlist['playlist']['track'] = tracks
f = open('playlist.json', 'w')
f.write(json.dumps(playlist, indent=4))
f.close()