def get_track(es_obj):
    """returns the track from the elasticsearch object"""
    es_ds = es_obj.get('_source', {})
    # iterate through ds
    track_met_options = ['track_number', 'track', 'trackNumber', 'track_Number']
    for tkey in track_met_options:
        track = es_ds.get(tkey, False)
        if track:
            return track
    # if that doesn't work try metadata
    es_met = es_ds.get('metadata', {})
    for tkey in track_met_options:
        track = es_met.get(tkey, False)
        if track:
            return track
    raise Exception('unable to find track for: {}'.format(es_obj.get('_id', '')))