async def fetch_order_book(self, symbol, limit=None, params={}):
    (await self.load_markets())
    request = {'currencyPair': self.market_id(symbol), 'groupByPrice': 'false'}
    if (limit is not None):
        request['depth'] = limit
    response = (await self.publicGetExchangeOrderBook(self.extend(request, params)))
    timestamp = self.safe_integer(response, 'timestamp')
    return self.parse_order_book(response, timestamp)
async def fetch_order_book(self, symbol, limit=None, params={}):
    (await self.load_markets())
    request = {'currencyPair': self.market_id(symbol), 'groupByPrice': 'false'}
    if (limit is not None):
        request['depth'] = limit
    response = (await self.publicGetExchangeOrderBook(self.extend(request, params)))
    timestamp = self.safe_integer(response, 'timestamp')
    return self.parse_order_book(response, timestamp)