How to use the ijson.backends.yajl2_cffi.items function in ijson

known_locations = []

    # TODO tagging should be takeout-agnostic
    def tagger(dt: datetime, point: geopy.Point) -> Tag:
        '''
        Tag points with known locations (e.g. work/home/etc)
        '''
        for lat, lon, dist, tag in known_locations:
            # TODO use something more efficient?
            if geopy.distance.distance((lat, lon), point).m  < dist:
                return tag
        else:
            return None


    for j in islice(ijson.items(fo, 'locations.item'), start, stop):
        dt = datetime.utcfromtimestamp(int(j["timestampMs"]) / 1000)
        if total % 10000 == 0:
            logger.info('processing item %d %s', total, dt)
        total += 1

        dt = pytz.utc.localize(dt)
        try:
            lat = float(j["latitudeE7"] / 10000000)
            lon = float(j["longitudeE7"] / 10000000)
            point = geopy.Point(lat, lon) # kinda sanity check that coordinates are ok
        except Exception as e:
            logger.exception(e)
            errors += 1
            if float(errors) / total > 0.01:
                raise RuntimeError('too many errors! aborting')
            else: