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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def run(self):
 """ Run import. """

        latest_track = Track.objects.all().order_by('-last_played')
        latest_track = latest_track[0] if latest_track else None
        
        importer = self.get_importer()
        tracks = importer.run()

        # Create/update Django Track objects for importer tracks.
        for track in tracks:
            # Only create/update if tracks with start times greater than what already exists are imported. 
            if not latest_track or not latest_track.last_played \
                    or track.start_time > latest_track.last_played:
                obj = self.lookup_track(track)
                # Don't update importing track that is regarded as the latest. This prevents start times from constantly incrementing.
                if latest_track and obj == latest_track:
                    print "[%s-%s]: Start time not updated as it is the latest track." % (track.title, track.artist)
                    continue

                # If no existing track object could be resolved, create it.
                if not obj:
                    print "[%s-%s]: Created." % (track.title, track.artist)
                    obj = Track.objects.create(title=track.title)
                    obj.length = track.length
                    roles = MusicCreditOption.objects.all().order_by('role_priority') 
                    role = roles[0].role_priority if roles else 1
                    obj.create_credit(track.artist, role)
                else:
                    print "[%s-%s]: Not created as it already exists." % (track.title, track.artist)
                
                # Update last played time to start time.
                obj.last_played = track.start_time
                obj.save()
                print "[%s-%s]: Start time updated to %s." % (track.title, track.artist, track.start_time)
            else:
                print "[%s-%s]: Not created as it has a past start time of %s (latest %s). " % (track.title, track.artist, track.start_time, latest_track.last_played)