How to use the kraken.error_handling.is_error function in kraken

def get_ohlc_kraken_result_processor(json_responce, currency, date_start, date_end):
    result_set = EMPTY_LIST

    if is_error(json_responce):

        msg = "get_ohlc_kraken_result_processor - error response - {er}".format(er=json_responce)
        log_to_file(msg, ERROR_LOG_FILE_NAME)

        return result_set

    if currency in json_responce["result"]:
        # "result":{"XXRPXXBT":[[1500873300,"0.00007037","0.00007055","0.00007012","0.00007053","0.00007035","104062.41283454",17],
        # [1500874200,"0.00007056","0.00007071","0.00007006","0.00007007","0.00007041","90031.72579746",33],
        for record in json_responce["result"][currency]:
            result_set.append(Candle.from_kraken(record, currency))

    return result_set

def get_history_kraken_result_processor(json_document, pair_name, timest):
    all_history_records = EMPTY_LIST

    if is_error(json_document):

        msg = "get_history_kraken_result_processor - error response - {er}".format(er=json_document)
        log_to_file(msg, ERROR_LOG_FILE_NAME)

        return all_history_records

    if pair_name in json_document["result"]:
        for rr in json_document["result"][pair_name]:
            all_history_records.append(TradeHistory.from_kraken(rr, pair_name, timest))

    return all_history_records

def get_open_orders_kraken_result_processor(json_document, pair_name):
    open_orders = EMPTY_LIST

    if is_error(open_orders) or "open" not in json_document["result"]:

        msg = "get_open_orders_kraken_result_processor - error response - {er}".format(er=json_document)
        log_to_file(msg, ERROR_LOG_FILE_NAME)

        return open_orders

    for order_id in json_document["result"]["open"]:
        new_order = Trade.from_kraken(order_id, json_document["result"]["open"][order_id])
        if new_order is not None:
            open_orders.append(new_order)

    return open_orders

def parse_order_id_kraken(json_document):
    """
    {u'result': {u'descr':
            {u'order': u'sell 10.00000000 XMRXBT @ limit 0.045000'},
            u'txid': [u'OY3ZML-PE3LG-L4NG7C']},
    u'error': []}
    """

    if is_error(json_document):

        msg = "parse_order_id_kraken - error response - {er}".format(er=json_document)
        log_to_file(msg, ERROR_LOG_FILE_NAME)

        return None

    if 'txid' in json_document['result']:
        return json_document['result']['txid']

    return None

def get_ticker_kraken_result_processor(json_document, pair_name, timest):

    if is_error(json_document):

        msg = "get_ticker_kraken_result_processor - error response - {er}".format(er=json_document)
        log_to_file(msg, ERROR_LOG_FILE_NAME)

        return None

    if pair_name in json_document["result"]:
        return Ticker.from_kraken(pair_name, timest, json_document["result"][pair_name])

    return None

def get_order_history_kraken_result_processor(json_document, pair_name):
    """
    json_document - response from exchange api as json string
    pair_name - for backwords compabilities
    """

    orders = EMPTY_LIST

    if is_error(json_document) or "closed" not in json_document["result"]:

        msg = "get_order_history_kraken_result_processor - error response - {er}".format(er=json_document)
        log_to_file(msg, ERROR_LOG_FILE_NAME)

        return orders

    for order_id in json_document["result"]["closed"]:
        new_order = Trade.from_kraken(order_id, json_document["result"]["closed"][order_id])
        if new_order is not None:
            orders.append(new_order)

    return orders